m^ 


Bulletin  ^-.k     'Ji'  Series  E,  Chemistry  and  Physics,  36 

l)l^:i*ARTMENT  OF  THE  INTERIOR 

UNITED  STATES  GEOLOGICAL  SURVEY 

CHARLES   D.   \VAL(;OTT,  Dikectok 


THE 


ACTION  OF  AMMONIUM  CHLORIDE 
UPON  SILICATES 


w:r.j^nj^  ^^^^igj-gmjES^u^orth  cl^rke 


GrKORCS^E    STIGI&ER 


WASHINGTON 

GOVERNMENT     PRINTING     OFFICE 

•1902 


u...t- 


SEP  3  0 


CONTENTS. 


Page. 

Introductory  statement 7 

Analcite . 8 

Lencite . . .  _ .  16 

The  constitntion  of  analcite  and  leucite 17 

Pollucite 21 

Natrolite 23 

Scolecite , 24 

Prehnite  ._ i 25 

The  trisilicic  acids 26 

Stilbite 29 

Heulandite ,  31 

Chabazite 32 

Thonisonite 34 

Lanmontite 35 

Pectolite 36 

Wollastonite 39 

Apophyllite j . .  39 

Datolite . _. 40 

Elseolite ■     40 

Cancrinite 41 

Sodalite .. 43 

The  feldspars 43 

Olivine 44 

Ilvaite 44 

Riebeckite  (?) 45 

^girite 46 

Calamine . . . ,  -^.-.^ ^ 47 

Pyrophyllite •_ 49 

Serpentine 51 

Phlogopite 51 

Lenchtenbergite 52 

Xanthophyllite 53 

The  action  of  ammonium  chloride  on  rocks 53 

Summary 57 


LETTER   OF   TRANSMITTAL. 


Department  of  the  Interior, 

United  States  Geological  Survey, 
Washington,  D.  C. ,  Septeniber  26,  1902. 
Sir:  I  have  the  honor  to  transmit  herewith  a  memoir  by  Messrs. 
Clarke  and  Steiger  on  the  action  of  ammonium  chloride  upon  silicates, 
with  the  recommendation  that  it  be  published  as  a  bulletin.  These 
researches  are  of  great  geological  importance  for  the  light  they  throw 
upon  the  rational  constitution  of  minerals.  They  are  based  on  a 
method  which  is  wholly  novel  and  which  is  capable  of  wide  applica- 
tion. The  work  is  most  creditable  to  the  authors  and  to  the  United 
States  Geological  Survey. 

Very  respectfully^  your  obedient  servant, 

George  F.  Becker, 

Geologist  in  Charge, 
Division  of  Chemical  and  Physical  Research. 

Hon,  Charles  D.  Walcott,  . 

Director  United  States  Geologiccd  Survey. 

5 


Digitized  by  the  Internet  Arciiive 

in  2010  with  funding  from 

Boston  Library  Consortium  IVIember  Libraries 


http://www.archive.org/details/actionofammoniumOOclar 


THE  ACTION  OF  AMMONIUM  CHLORIDE  UPON 

SILICATES. 


By  Frank  Wigglesworth  Clarke  and  George  Steiger. 


INTRODUCTORY   STATEMENT. 

In  a  series  of  investigations  by  Clarke  and  Schneider,  which  wer^. 
carried  out  in  the  laboratory  of  the  United  States  Geological  Survey 
between  the  years  1889  and  1892,"  a  number  of  reactions  were  studied 
which  shed  some  light  upon  the  constitution  of  the  natural  silicates. 
Among  these  reactions  two  were  of  x)eculiar  interest,  on  account  of 
their  simplicity  and  the  ease  with  which  they  could  be  applied. 

First,  in  the  case  of  talc,  it  was  found  that  one-fourth  of  the  silica 
could  be  liberated  by  ignition;  and  that  the  fraction  thus  set  free 
was  measurable  by  solution  in  aqueous  sodium  carbonate.  This 
reaction  suggests  that  other  acid  metasilicates  may  behave  in  a  sim- 
ilar way,  and  that  we  perhaps  have  a  means  of  discrimination  between 
such  salts  and  other  compounds  which  simulate  them.  In  other 
words,  an  acid'metasilicate  may  be  experimentally  distinguished 
from  a  pseudo-metasilicate  by  the  way  in  which  it  splits  up  when 
ignited.  Evidence  bearing  upon  this  supposition  will  be  found  in 
the  present  paper. 

The  second  of  the  reactions  just  referred  to  is  that  between  dry 
ammonium  chloride,  at  its  temperature  of  dissociation,  and  various 
silicates,  different  minerals  being  very  differently  attacked.  Some 
are  completely  decomposed,  others  are  affected  but  slightly,  and  in 
certain  cases  substitutions  are  produced  of  a  most  suggestive  char- 
acter. To  a  certain  extent,  the  two  reactions  overlap;  that  is,  each 
one  bears  somewhat  upon  the  other,  and  hence  both  have  received 
consideration  in  the  present  series  of  researches. 

In  the  earlier  stages  of  our  work  the  several  silicates  which  were 
studied  were  heated  with  dry  ammonium  chloride  in  open  platinum 
crucibles.  The  temj)erature  chosen  was  350°,  at  which  point  the 
chloride  breaks  up  into  gaseous  hydrochloric  acid  and  free  ammonia, 

"Bulls.  U.  S.  Geol.  Survey  No.  78,  p.  11;  No.  90,  p.  11;  No.  113,  pp.  87,  34. 


8  ACTION    OJF    AMMONIUM    CHLORIDE    ON    SILICATES.       [bull.  207. 

and  in  this  way  partial  changes  were  effected.  Later,  the  heatings 
were  performed  in  sealed  combustion  tubes,  and  then  the  reaction 
proved  to  be  much  more  far-reaching.  In  nearly  every  case  the 
material  taken  for  investigation  was  ground  up  into  one  large,  uni- 
form sample,  upon  which  all  the  experiments  were  performed,  and 
in  that  way  the  results  obtained  are  comparable  with  one  another. 
The  few  exceptions  to  this  rule  of  procedure  will  be  noticed  at  the 
proper  places.  In  testing  for  soluble  silica,  a  standard  solution  of 
sodium  carbonate,  containing  250  grams  to  the  liter,  was  used,  and 
here  again  the  experimental  conditions  liave  been  kept  uniform.  So 
much  premised,  we  may  proceed  to  the  description  of  our  investiga- 
tions, species  by  species,  in  detail. 


ANALCITE. 

Analcite,  from  many  points  of  view,  is  a  species  of  X3eculiar  inter- 
est, and  of  late  j^ears  it  has  received  a  great  deal  of  attention.  Its 
formula  may  be  written  in  various  ways,  especially  as  regards  the 
interpretation  of  its  one  molecule  of  water;  but  evidence  too  often 
has  yielded  before  preconceived  opinion.  Additional  evidence  is  now 
available,  partly  from  the  experiments  of  Friedel,  and  partly  from 
the  data  obtained  during  the  present  investigation. 

The  analcite  first  examined  by  us  was  in  well-developed  crystals 
from  Wassons  Bluff  in  Nova  Scotia.  A  uniform  sample  was  pre- 
pared, as  usual,  and  the  analysis,  given  below,  is  contrasted  with  the 
theoretical  composition  required  by  the  accepted  empirical  formula 
NaAlSigOg .  HgO. 


Found. 

Calculated. 

SiOa                                                ...              .        

57.06 

21.48 

.13 

.16 

12.20 

.58 

8.38 

54.55 

A1203 

23.18 

Fe.,0, 

CaO 

Na^O 

14.09 

H^Oat  100°  

H^O  over  100° -.          ..   

8.18 

99.99 

100.00 

Fractions  of  ivater. 

At  100° 0.58 

At  180° . 1.16 

At  260° 3.64 

At  300° 1.57 

Low  redness. ." 1. 90 

Full  redness .11 

Blast none 

8.96 


CLARKE  AN 
STEIGER. 


"]  ANALCITE.  9 


The  fractional  water  determinations  were  made  by  heating  in  an 
air  bath  to  constant  weiglit  at  each  teniperatnre  np  to  300°,  and 
finally  over  the  direct  flame.  The  first  fraction,  at  100°,  is  evidently 
hygroscopic  or  extraneous  water,  which  can  be  disregarded.  The 
remainder  of  the  water,  8.38  per  cent,  belongs  to  the  species.  The 
significance  of  the  analj^tical  figures  will  be  considered  later. 

Upon  boiling  the  powdered  analcite  with  the  standard  sodinm  car- 
bonate solution,  0.73  per  cent  of  silica  was  extracted.  After  ignition 
the  mineral  in  two  determinations  yielded  1.46  and  1.38  per  cent, 
respectively.  The  splitting  off  of  silica  is,  therefore,  very  slight;  and 
one  of  the  formulae  proposed  by  Doelter,'^  NagAlgSiaOg+SHaSiOg,  may 
be  set  aside  as  improbable.  Metasilicic  acid,  or  an  acid  metasilicate, 
can  hardly  be  present  in  analcite ;  although  the  possibility  of  a  neutral 
metasilicate,  as  indicated  by  the  empirical  formula,  is  not  excluded. 
If  Doelter's  formula  were  correct,  one-half  of  the  silica  should  be 
liberated  by  ignition. 

Upon  heating  analcite  with  dry  ammonium  chloride,  notable  results 
were  obtained  even  in  an  open  platinum  crucible.  Sodium  chloride 
was  formed,  which  could  be  leached  out  by  water  and  measured, 
while  ammonia,  free  from  chlorine,  was  retained  by  the  residue  to  a 
notable  and  surprisingly  stable  degree.  The  experiments  in  detail 
were  as  follows: 

A.  Analcite,  mixed  with  four  times  its  weiglit  of  ammonium  chloride,  was 
heated  for  four  hotirs  to  350°.  There  was  a  gain  in  weight  of  2.18  per  cent,  and 
6.10  per  cent  of  soda,  or  one-half  of  the  total  amount,  was  converted  into  NaCl, 
which  was  leached  out  by  water,  examined  as  to  its  purity,  and  weighed.  In  the 
residue  1.20  per  cent  of  silica  was  extracted  by  sodium  carbonate,  showing  that 
no  more  splitting  off  had  occurred  than  was  previously  observed.  The  gain  in 
weight,  as  will  be  seen  from  subsequent  experiments,  is  due  to  the  fact  that  all  of 
the  NH4CI  had  not  been  driven  off,  or  else  that  more  water  was  retained. 

B.  Analcite  was  ground  up  with  four  times  its  weight  of  NH4CI,  heated  for 
several  hours,  reground  with  another  fourfold  portion  of  chloride,  and  heated  to 
350°  for  twenty-one  hours.  Grain  in  weight,  0.08  laer  cent.  5.57  per  cent  of  soda 
was  extracted  as  chloride. 

C  Analcite  heated  to  350°  for  eight  hours  with  four  times  its  weight  of  NH^Cl. 
Loss  of  weight,  0.10  per  cent. 

D.  Six  grams  of  mineral  and  28  of  chloride,  mixed  by  thorough  grinding,  were 
heated  to  350°  for  fourteen  hours;  then  were  reground  with  28  grams  of  fresh 
NH^Cl  and  heated  for  thirty-five  hours.  Loss  of  weight,  0.18  per  cent.  5.07  per 
cent  of  soda  was  extracted  as  chloride,  plus  0.14  of  ammonium  chloride  unexpelied. 
2.03  per  cent  of  silica  was  rendered  soluble  in  sodium  carbonate. 

So  far  three  facts  are  noticeable.  First,  the  weight  of  the  mineral 
after  treatment  is  almost  exactly  the  same  as  before,  showing  that 
gains  and  losses  have  balanced  each  other.  Secondly,  little  silica  has 
been  split  off.  Thirdly,  approximately,  but  not  rigorously,  one-half 
of  the  soda  has  been  converted  into  NaCl.  In  A  it  was  exactly  half; 
in  the  other  experiments,  a  little  less  than  half.  Furthermore,  in  the 
sodium  chloride  dissolved  out,  there  is  only  a  very  little  ammonium 


aNeiies  Jahrbuch,  1890,  Vol.  I,  p.  133. 


10 


ACTIOIT    OF    AMMONIUM    CHLOEIDE    ON    SILICATES.       [bull.  207. 


chloride,  amounting  at  most  to  0.14  per  cent,  calculated  upon  the 
weight  of  the  original  mineral. 

In  the  residue  of  the  analcite  after  extraction  of  sodium  chloride, 
abundant  ammonia  can  be  detected,  with  either  no  chlorine  or  at 
most  a  doubtful  trace.  If,  however,  the  unleached  mineral,  still 
retaining  its  sodium  chloride,  be  heated  strongly,  ssby,  from  400°  up 
to  redness,  NH4CI  is  regenerated  and  given  off.  Its  absence,  as  such, 
both  from  the  leach  and  the  residue  was  repeatedly  proved.  The 
ammonia  and  water  retained  by  the  analcite  after  healing  to  350°  with 
ammonium  chloride  were  several  times  determined,  and  the  following 
percentages,  still  reckoned  on  the  original  mineral,  were  found : 


NH3. 

H 

0. 

InB                                .-   

2.03 
2.19 
2.36 
2.35 
2.06 

2.25 

InC                                  - 

2.00 

InD                                  -     ---   

1.89 

(( 

<< 

Mean        - - -   - -  -- 

2.20 

2,04 

Correcting  the  ammonia  for  the  0.14  of  IsrH4Cl  found  in  D,  the  mean 
value  becomes  2.15.  The  determinations  of  it  were  made  by  three 
distinct  methods,  and  there  is  no  possible  doubt  as  to  its  presence. 

The  composition  of  the  analcite  after  the  treatment  with  ammonium 
chloride  may  now  be  considered,  with  the  subjoined  combination  of 
the  data.  The  ISTaCl  in  A,  11.50  per  cent,  was  in  material  which  had 
gained  2.18  per  cent,  and  is  subject  to  a  correction  which  reduces  the 
figure  to  11.26.  In  B,  C,  and  D  the  corresponding  correction  is  so 
small  that  it  may  be  neglected.  The  last  column  gives  the  composi- 
tion of  the  leached  residue,  recalculated  to  100  per  cent,  after  deduc- 
tion of  NaCl  and  the  soluble  silica.  The  letters  refer  back  to  the 
several  experiments,  and  the  little  iron  is  included  with  the  alumina. 


A. 

B. 

C. 

D. 

Average. 

Residue. 

Sol  SiOa 

1,20 

2.03 

54.96 

21.37 

.16 

9.57 

7.12 

2.21 

1.89 

1.61 

54.96 

21.37 

.16 

10.44 

7.12 

2.15 

2.04 

Insol.  SiO^ 

62.59 

AloOo 

34.34 

CaO 

.18 

NaCl      

11.26 

10,50 

Na^O  '                            -     -- 

8.11 

NH3      

2.03 

2  25 

2.19 
2.00 

2.46 

H2O          

2.32 

99.31 

99.85 

100, 00 

'\^iVr]  ANALCITE.  11 

The  results  thus  obtained  with  aualeite  from  Nova  Scotia  were  so 
remarkable  that  further  investigation  seemed  to  be  needed  upon 
material  of  different  origin,  and  with  variation  in  the  details  of 
manipulation.  The  new  experiments,  which  have  led  to  highly  inter- 
esting consequences,  are  now  to  be  described. 

To  the  kindness  of  President  Regis  Chauvenet,  of  the  State  School 
of  Mines,  we  are  indebted  for  a  liberal  supply  of  well-crystallized 
analcite  from  North  Table  Mountain,  near  Golden,  Colo.,  of  which  a 
uniform  sample  of  about  80  grams  was  prepared.  An  analysis  of 
the  mineral  gave  the  following  results: 

SiO^ 55.72 

AI2O3 23.06 

CaO .17 

NaaO , 12.46 

H^Oat  100° 0.13 

H2O  above  100°  _ : 8. 26 

99. 80 
Water  by  fractions. 

At  100° 0.13 

At  180° .75 

At  260° :..-. 2.44 

At  300° 1.28 

At  350° 1 1.76 

At  redness . . 2. 03 

8.39 
Above  a  low  red  heat  no  f  urtliei-  loss  of  weight  was  observed.  Upon 
boiling  the  powdered  mineral  for  fifteen  minutes  with  the  standard 
solution  of  sodium  carbonate,  0.45  per  cent  of  silica  was  dissolved. 
After  ignition,  0.57  per  cent  was  soluble,  which  is  practically  the 
same  amount.  No  silica  was  split  off  by  heating.  The  experiments 
with  ammonium  chloride  fall  into  two  series.  The  first  of  these  was 
conducted  precisely  as  in  the  case  of  the  Nova  Scotian  material, 
namely,  hy  grinding  the  powdered  mineral  into  an  intimate  mixture 
with  four  times  its  weight  of  the  chloride,  and  heating  in  an  open 
crucible.  In  three  cases  the  material,  after  volatilization  of  the 
ammonium  chloride,  was  reground  with  a  fresh  amount  of  the  salt, 
and  then  heated  again.  The  temperature  and  duration  of  the  experi- 
ments were  purposely  somewhat  varied.  After  heating,  the  material 
was  leached  out  with  water,  the  sodium  chloride  which  had  been  formed 
was  estimated,  and  in  the  residue  the  fixed  ammonia  was  determined. 
In  this  series  there  were  four  experiments,  with  results  as  follows : 


Hours 
heated. 

Temper- 
ature. 

Soda  re- 
moved. 

Ammonia 
in  residue. 

A 

28 
8i 

300 
350 

4.75 
6.36 

2.04 

B 

2.88 

C 

26 

350 

3.76 

1.72 

D 

5 

340-380 

6.70 

2.85 

12 


ACTION    OF    AMMONIUM    OHLOEIDE    ON    SILICATES.       [bull.  207. 


In  the  aiialcite  from  Nova  Scotia  the  ammonia  retained  by  the 
leached  residue  ranged  from  2.03  to  2.36  per  cent,  while  the  extracted 
soda  varied  from  5.07  to  6.10.  In  two  of  the  new  exi)eriments  these 
figures  are  perceptibly  exceeded,  and  they  represent  the  shortest 
duration  of  heating.  Prolonged  heating  seems  to  be  undesirable,  and 
seems  to  undo  a  part  of  the  reaction  which  has  taken  place;  otherwise 
the  results  obtained  are  of  the  same  order  as  their  predecessors. 
About  one-lialf  of  the  soda  in  the  analcite  is  converted  into  chloride, 
while  variable  ammonia  is  retained. 

In  the  second  series  of  experiments  a  sealed  tube  was  substituted 
for  the  open  crucible.  The  powdered  analcite  was  intimately  ground 
with  four  times  its  weight  of  ammonium  chloride,  as  before,  and  then 
heated  to  350°  in  a  tube  furnace  for  from  four  to  eleven  hours.  Under 
these  conditions  practically  the  whole  of  the  soda  in  the  mineral  was 
converted  into  sodium  chloride,  while  all  of  the  liberated  ammonia 
was  absorbed  by  the  residual  silicate.  Upon  leaching  the  contents 
of  the  tube  with  water,  to  remove  sodium  and  ammonium  chlorides, 
a  residue  was  obtained  which  exhibited  constant  composition  whether 
dried  at  100°  or  at  the  ordinary  temperature  of  the  air.  Three 
samples  of  the  residue  were  prepared  and  analyzed;  other  samples 
were  partially  examined  and  used  for  subsidiary  experiments.  The 
three  analyses,  lettered  for  future  reference,  were  as  follows,  the 
analcite  itself  being  included  in  the  table  for  comparison : 


Analcite. 

Residue  A. 

Residue  B. 

Residue  C. 

SiO^ .--- 

AI.Oo                   ...   ...   

55.72 

23.06 

.17 

12.46 

61.93 

25.21 

61.68 
25.88 

61.79 
25.24 

CaO  -              . ..;... 

]Sra.,0                 

.40 
7.28 
4.50 

.22 
6.95 
4.91 

.28 

NH3             '. ...  .. 

7.71 

H20             ..  ... 

8.39 

5.01 

99.80 

99.27 

99.09 

100. 03 

Residue  C  was  prepared  with  the  greatest  care,  and  was  air  dried. 
Exposed  over  sulphuric  acid  in  a  vacuum  desiccator  for  fourteen  days, 
it  lost  in  weight  onlj^  0.08  per  cent.  Tested  for  chlorine,  only  a  slight 
trace  could  be  recognized,  but  upon  boiling  for  fifteen  minutes  with 
sodium  carbonate  solution  it  yielded  1.97  of  soluble  silica.  After 
ignition  only  1.70  of  silica  Avas  soluble,  or  somewhat  less  than  before. 
Upon  heating  to  constant  weight  at  300°,  only  0.46  per  cent  was  lost, 
but  at  350°  it  slowly  decomposed,  giving  off  ammonia.  At  300°  the 
compound  is  stable. 

The  0.28  per  cent  of  soda  remaining  in  residue  C  may  be  regarded 
as  representing  unaltered  analcite,  doubtless  coarser  particles  which 


CLARKE  and! 
STEIGBR.      J 


ANALCITE. 


13 


escaped  complete  transformation.  It  corresponds  to  1.08  per  cent  of 
analcite,  which,  together  with  the  1.97  of  soluble  silica  and  tlie  0,46 
of  water  lost  below  300°,  may  be  deducted  from  the  substance  in 
order  to  obtain  the  composition  of  tlie  definite  compound.  The  latter 
amounts  to  94.72  per  cent  of  the  total  residue,  and  agrees  very  nearly 
in  composition  with  the  formula 

2NH3.H20.Al203.4Si02. 

Recalculating  the  94.72  of  residue  to  100  per  cent,  we  get  the  follow- 
ing comparison  between  analysis  and  theory : 


SiO,- 
A1,0,, 

H,0. 


Found. 


61.07 

26. 15 

8.14 

4.64 


100. 00 


Calculated. 


60.92 

25.  88 

8.63 

4.57 


100. 00 


Written  in  rational  form  the  compound  becomes  equivalent  to  an 
anhydrous  ammonium  analcite, 

NH.AlSiPe; 
that  is,  analcite  in  which  sodium  has  been  replaced  by  ammonium. 
From  this  point  of  view  the  reaction  between  analcite  and  ammonium 
chloride  becomes  a  simple  case  of  double  decomposition,  and  is  per- 
fectly intelligible.  To  establish  this  conclusion,  however,  corrobora- 
tive experiments  were  necessary. 

In  the  first  place,  the  observed  equivalency  between  the  sodium 
lost  and  the  ammonia  gained  might  be  due  to  a  mere  coincidence,  and 
so  far  be  illusory.  One  atom  of  sodium,  taking  chlorine  from  ammo- 
nium chloride,  liberates  one  molecule  of  ammonia,  the  amount  which 
the  analcite  residue  has  retained.  Suppose  more  ammonia  were  pres- 
ent; could  it  be  absorbed? 

To  answer  this  question  another  tube  was  prepared,  with  the  usual 
mixture  of  analcite  and  ammonium  chloride.  This  was  covered  by  a 
loose  plug  of  glass  wool,  in  front  of  which  we  placed  enough  pure 
lime  to  liberate  about  double  the  normal  amount  of  ammonia.  The 
tube  was  then  sealed,  and  heated  to  350°,  as  in  the  previous  experi- 
ments. Upon  opening  the  tube,  a  strong  outrush  of  ammonia  was 
noticed;  but  in  the  leached  and  thoroughly  washed  residue,  only  7.52 
per  cent  of  ammonia  was  found.  This  quantity  agrees  with  that  from 
the  previous  samples,  and  shows  that  the  limit  of  the  reaction  has 
been  practically  reached.  One  molecule  of  ammonia  is  retained,  and 
no  more. 

Still  another  experiment  was  tried  upon  a  portion  of  the  residue 
marked  C.     If  the  compound  is  really  an  ammonium  salt,  it  should 


14  ACTION    OF    AMMONIUM    CHLOKIDE    ON    SILICATES.       [bull.  207. 

be  decomposable  by  caustic  soda  in  such  a  way  as  to  reverse  the  reac- 
tion by  which  it  had  been  obtained.  The  substance,  however,  is  very 
insoluble,  so  that  the  reaction  takes  place  slowly.  To  phenol  phthal- 
ein  it  is  absolutely  neutral,  and  with  Nessler's  reagent  it  reacts  only 
after  long  standing. 

To  settle  the  question  a  weighed  portion  of  the  compound  was  boiled 
in  a  distilling  flask  with  a  10  per  cent  solution  of  sodium  hydroxide, 
to  which  water  was  added  from  time  to  time.  The  distillate  was  col- 
lected in  a  tube  containing  aqueous  hydrochloric  acid;  and  the 
ammonia  which  passed  over  was  weighed,  ultimately  as  chloroplati- 
nate.  Bj^  four  hours'  boiling  6.90  per  cent  of  ammonium  was  driven 
off  and  determined;  and  the  residue  remaining  in  the  flask,  after 
washing  until  no  alkaline  reaction  could  be  detected  in  the  wash- 
water,  was  examined  for  soda,  of  which  10.41  per  cent  was  found. 
The  anticipated  reaction  had  taken  place,  although  not  completely; 
it  was  enough,  however,  to  confirm  our  opinion,  and  to  establish  the 
nature  of  the  new  compound  beyond  reasonable  doubt.  Other  con- 
firmation was  obtained  later,  from  the  study  of  leucite. 

The  foregoing  paragraphs  now  enable  us  to  understand  a  phenome- 
non which  we  observed  in  our  work  with  the  open  crucible.  In  that 
case  a  partial  reaction  takes  place  between  the  analcite  and  the 
ammonium  chloride,  producing,  as  in  the  sealed  tube,  a  mixture  of 
an  ammonium  alumino-silicate  with  sodium  chloride:  the  two  sub- 
stances being  separable  by  leaching.  But  if,  instead  of  leaching,  the 
mixture  be  heated  to  full  redness,  ammonium  chloride  is  re-formed 
and  given  off,  leaving  a  residue  which  contains  little  or  no  sodium 
chloride,  and  is  wholly  insoluble,  or  almost  so,  in  water.  That  is, 
the  reaction  which  occurs  at  350"  is  reversed  at  the  higher  temerature, 
and  anhydrous  analcite,  or  an  isomer  of  it,  is  regenerated.  Ammo- 
nium and  sodium  again  change  places,  and  the  original  state  of  molec- 
ular equilibrium  is  restored. 

What,  now,  is  the  nature  of  the  product  obtained  in  the  open  cru- 
cible after  sodium  chloride  has  been  removed?  Is  it  a  definite  inter- 
mediate compound  or  an  indeterminate  mixture?  At  first  we  were 
inclined  to  accept  the  first  of  these  alternatives,  and  we  assigned  to 
the  substance  the  formula  IIaNa3Al4Sig024.NH3,  in  which  the  ammonia 
plays  a  part  equivalent  to  that  of  water.  In  this  expression  we  were 
influenced  by  the  researches  of  Friedel,"  who  had  shown  that  ammonia 
could  in  part  replace  the  "zeolitic"  water  of  analcite;  but  it  now 
appears  that  the  phenomenon  observed  by  him  is  quite  distinct  from 
that  discovered  by  us,  and  is,  indeed,  of  an  entirely  different  order. 
We  may,  therefore,  in  accordance  with  our  new  data,  rearrange  the 
formula,  transforming  it  to  that  of  an  ammonium  salt,  HNa2]S'H4Al4 
Si8024,  the  agreement  with  the  analytical  figures  being  approximate 
only.     The  results  obtained  are  not  sharp  enough  for  certainty. 

This  product  we  are  now  inclined  to  regard  as  a  mixture,  although 

a  Bull.  Soc.  min.  Prance,  Vol.  XIX,  p.  94,  1896, 


CLARKE  AND"! 
STEIGER.      J 


ANALCITE. 


15 


it  is  not  strictly  intermediate  between  analcite  and  its  final  ammoniiini 
derivative.  Only  half  of  the  eliminated  sodium  has  been  replaced 
by  ammonium,  while  hydrogen,  or  water,  makes  up  the  deficiency. 
It  seems  probable  that  the  reaction  in  the  sealed  tube  and  that  in  the 
open  crucible  are  at  first  essentially  the  same,  but  that  in  the  latter 
case  secondary  reactions  follow,  which  cause  the  variations  in  the 
final  riesults.  In  the  sealed  tube  the  element  of  pressure  comes  into 
play,  and  the  reaction  is  complete.  In  the  open  crucible  pressure  is 
lacking;  some  ammonia  escapes  fixation  and  reacts  upon  a  jjart  of  the 
sodium  chloride  which  was  at  first  formed ;  hence  the  composition  of 
the  leached  residue  is  essentially  modified.  This  residue  may  be  a 
definite  compound,  but  the  case  in  its  favor  is  unproved  and  the 
presumption  is  rather  against  it. 

The  most  remarkable  fact  developed  by  the  foregoing  experiments 
is  the  easy  replaceability  of  the  soda  in  analcite.  This  replaceability, 
however,  is  not  limited  to  the  substitution  of  ammonium  for  sodium; 
it  appears  to  extend  to  other  bases  as  well,  and  this  we  have  proved 
in  the  case  of  silver.  This  is  illustrated  by  three  experiments  upon 
the  Colorado  analcite,  as  follows: 

A.  Analcite,  intimately  mixed  with  dry  silver  nitrate,  was  heated  in  a  sealed 
tube  to  400°  for  four  hours. 

B.  Analcite  and  silver  nitrate  were  heated  in  a  sealed  tube  to  250°  for  four  hours. 

C.  Ammonium  analcite,  mixed  with  dry  silver  nitrate,  was  heated  in  a  sealed 
tube  to  250°  for  four  hours. 

All  the  products  of  these  heatings  were  leached  with  water,  and 
washed  until  the  filtrates  gave  no  test  for  silver;  the  residues  were 
then  dried  on  the  water  bath.  The  product  in  each  case  was  a  white 
powder  not  differing  in  appearance  from  the  original  mateKal. 

The  analyses  of  the  different  portions  are  given  below,  together  with 
the  composition  of  the  theoretical  compound,  AgAlSigOg.HaO,  which 
is  given  in  column  D. 


A. 

B. 

C. 

D. 

SiOa 

41.31 

16.44 

37.45 

.85 

4.29 

40.08 
16.29 
36.91 

.ai 

5.86 

42.69 

18.22 
32.01 

.68 
6.08 

.69 
none 

39.35 

A1203  -    - 

16.72 

AgjO . 

38.03 

NazO 

H,0 -       .. 

5.90 

NH3 

Nitrates _  .  ._ 

none 

none 

100. 34 

99.95 

100. 37 

100. 00 

From  preparation  A,  13.13  per  cent  of  the  soda  in  the  original  min- 
eral was  found  in  the  leach  water;  and  in  B,  12.57  per  cent.  These 
quantities  are  slightly  in  excess  of  the  amount  actually  present  in  the 
analcite,  for  the  reason  that  a  little  other  material  which  passed  into 


16  ACTION    OF    AMMONIUM    CHLORIDE    ON    8ILICATES.       [bull.  207. 

the  filtrates  was  not  separated  from  the  soda.  It  is  enough  to  show 
that  a  true  silver  analcite  has  been  formed,  and  that  the  transforma- 
tion is  practically  complete.  A  similar  reaction  takes  place  between 
silver  nitrate  and  chabazite,  but  the  product  as  yet  has  not  been 
exhaustivel}^  examined.  The  reaction,  it  will  be  observed,  is  analo- 
gous to  that  by  which  silver  ultramarine  is  produced,  and  it  suggests 
a  promising  line  of  experimentation  for  the  future. 

LEUCITE. 

Between  analcite  and  leucite  the  closest  analogies  have  long  been 
recognized.  The  two  minerals  have  similar  composition,  they  resemble 
each  other  in  crystalline  form,  and  they  yield,  upon  alteration,  prod- 
ucts of  the  same  order.  Recently  also,  analcite,  like  leucite,  has  been 
identified  as  a  not  uncommon  constituent  of  volcanic  rocks;  analcite 
basalt  being  a  good  example.  In  view  of  these  resemblances  it  was 
plainly  desirable  to  compare  the  minerals  by  means  of  the  ammonium 
chloride  reaction,  a  task  which  has  been  performed  with  satisfactory 
results. 

In  a  preliminary  experiment  a  sample  of  leucite  taken  without 
regard  to  purity  was  heated  with  ammonium  chloride  to  350°  in  a 
sealed  tube.  Potassium  chloride  was  formed  corresponding  to  18.06 
per  cent  of  potash,  and  in  the  leached  residue  6.90  jjer  cent  of 
ammonia  was  found.  The  foreseen  reaction  had  occurred,  and  more 
careful  work  was  accordingly  undertaken. 

Our  material  consisted  of  a  large,  irregular  crystal  of  leucite  from 
Vesuvius,  which  yielded  about  20  grams  of  the  pure  mineral.  This 
was  ground  to  a  uniform  samj)le,  and  a  portion  of  it  was  analyzed; 
the  analysis  will  be  given  presently.  The  sealed-tube  experiments 
were  conducted  precisely  as  in  the  case  of  analcite,  and  they  confirmed 
both  the  preliminary  test  and  our  anticipations.  Chlorides  were 
formed  equivalent  to  18.53  per  cent  of  potash,  1.08  of  soda,  and  0.08 
of  alumina;  the  reaction,  therefore,  was  very  nearly  complete.  The 
leached  residue  was  then  analyzed,  and  the  data,  compared  with  the 
analysis  of  the  original  mineral,  were  as  follows: 


Leucite. 


SiO, '  55.40 

AlA     '  33.69 

CaO.           j  .16 

K.,0 19.54 


Residue. 


60.63 

26.44 

trace 

.50 


Na/) 1.25  .25 

NH;, 7.35 

H.,0 .24  5.17 

100. 28  100. 34 


CLAIIKE  AN 
STEIGEU 


"1 


LEUOITE. 


17 


Leucite,  then,  gives  the  s;uue  reaction  as  anal(!ite  and  yields  tlio 
same  ammoninm  componnd.  A  closer  agreement  in  the  comi)osition 
of  the  latter  could  not  reasonably  be  demanded.  Ammonium  leucite 
is  formed  in  both  cases  by  ordinary  double  decomposition  in  a  state 
of  approximate  purity;  the  first  silicate  of  ammonium,  we  think, 
which  has  ever  been  prepared. 

As  a  further  check  upon  the  results  so  far  obtained,  an  attempt  was 
made  to  transform  ammonium  leucite  into  the  corresponding  lime 
salt,  CaAljSijOia,  by  fusion  with  calcium  chloride.  The  ammonium 
leucite  was  mixed  with  a  saturated  solution  of  calcium  chloride,  which 
Avas  evaporated  to  dryness,  then  heated  gradually  to  dehydration,  and 
finally  fused.  Ammonium  chloride  was  given  off  and  identified. 
Upon  treating  the  fused  mass  with  water,  filtering  and  thoroughly 
washing  the  residue,  a  white  powder  was  obtained  which,  after  drying 
at  100°,  was  analyzed.  It  was  also  examined  microscopically  by  Mr. 
J.  S.  Diller,  who  found  it  to  consist  of  apparently  isotropic  grains, 
showing  traces  of  incipient  crystallization.  The  following  analysis  is 
contrasted  with  the  theoretical  composition  of  calcium  leucite,  from 
which  it  varies  considerably. 


Found. 

Calculated. 

SiO,  

54.35 

26. 23 

17.38 

.16 

.25 

.28 

1.24 

60.30 

Aip..      ...         .         

25.  63 

CaO 

14.07 

KjO 

Na.,0                           .                        

CI .  

Loss  on  ignition 

99.89 

100.00 

Evidently  the  desired  salt  was  not  definitely  obtained,  and  the 
product  appears  to  be  a  mixture.  The  reaction,  however,  tends  in 
the  right  direction,  and  deserves  further  study  under  other  condi- 
tions. Probably  the  water  which  was  present  in  the  mixture  of  sili- 
cate and  chloride  took  part  in  the  changes  produced,  although  of  this 
we  can  not  be  certain.  It  is  interesting  to  note  that  the  product 
obtained  approximates  in  composition  to  the  meteoric  mineral  mas- 
kelynite,  which  is  regarded  by  Groth  as  probably  equivalent  to  a 
calcium  leucite. 


THE   CONSTITUTION    OF  ANALCITE  AND   LEUCITE. 

In  all  of  the  earlier  attempts  to  discuss  the  constitution  of  analcite 
the  molecule  of  water  which  it  contains  has  been  a  chief  element  of 
uncertainty.     Should  it  be  regarded  as,  representing  hydroxyl  or  as 

9506— No.  207—02 2 


18  ACTION    OF    AMMONIUM    CHLORIDE    ON    SILICATES.       [bull.  207. 

water  of  crystallization?  That  question  arose  first  of  all.  Under  the 
first  interpretation  analcite  became  a  diorthosilicate :  AlNaHjSigO^; 
under  the  latter  its  equivalency  with  leucite  appeared .  The  researches 
of  Friedel,  however,  have  settled  this  question  in  part,  and  whatever 
the  function  of  the  water  may  be  it  is  something  outside  of  the  true 
chemical  molecule;  for  all  the  water  can  be  expelled  from  analcite 
bjT^  heat,  without  destruction  of  the  crystalline  nucleus,  the  anhydrous 
salt,  and  it  is  taken  up  again  upon  exposure  of  the  dehydrated  min- 
eral to  moist  air.  But  whatever  its  mode  of  union  may  ultimately 
prove  to  be,  the  amount  of  water  in  analcite  corresponds  to  the  simple 
molecular  ratio  which  is  shown  in  the  ordinary  formula  of  the  species. 
One  molecule  of  analcite  holds  a  certain  definite  number  of  water 
molecules,  and  Friedel's  observations  are  not  incompatible  with  the 
idea  that  these  are  retained  with  varying  degrees  of  tenacity.  This 
idea  is  suggested  by  the  various  series  of  fractionation  experiments 
which  have  been  made  from  time  to  time  by  independent  workers, 
even  though  the  data  are  not  by  any  means  concordant.  Thus 
Lepierre  "  found  that  half  the  water  of  analcite  was  driven  off  at  or 
below  300°,  the  other  half  above  440°.  In  our  own  experiments  three- 
fourths  were  expelled  at  300°,  the  remaining  fourth  being  held  up  to 
a  much  higher  but  undetermined  temperature.  In  both  series  the 
water  fractions  are  represented  by  fourths,  but  Friedel's  experi- 
ments* indicate  a  continuity  of  loss  in  weight  of  a  quite  dissimilar 
order.  Friedel  holds  that  all  of  the  water  fractionations  heretofore 
made  upon  analcite  are  fallacious,  and  that  no  definite  fractions  can 
be  identified — a  conclusion  strongly  supported  by  his  own  data,  even 
though  the  proof  is  not  absolutely  positive.  The  most  that  can  be 
said  is  that  the  weight  of  evidence  so  far  is  in  favor  of  Friedel's 
contention,  but  that  additional  investigation  is  necessary  in  order  to 
reconcile  all  discrepancies.  The  full  significance  of  the  water  in 
analcite  remains  unknown. 

Eliminating  the  water  from  analcite,  the  empirical  formulse  for 
both  analcite  and  leucite  appear  at  once  to  be  identical  in  form  and 
to  represent  salts  of  ordinary  metasilicic  acid.  Indeed,  both  minerals 
have  been  commonly  regarded  as  metasilicates;  but  upon  this  iDoint 
the  j)roduction  of  the  ammonium  derivatives  now  sheds  a  new  light. 
In  the  formation  of  the  latter  compounds  the  fixed  bases  of  the 
original  salts  have  been  replaced  by  a  volatile  base,  and  the  substances 
so  formed  split  up  upon  ignition  in  such  a  way  as  to  give  evidence 
regarding  their  constitution. 

For  example,  if  ammonium  leucite  is  a  true  metasilicate,  a  salt  of 
the  acid  HjSiOg,  it  should  break  up,  when  ignited,  in  accordance 
with  the  following  equation : 

2NH4Al(Si03)2=Al2(Si03)3  +  2NH3-j-Il20-f-Si02; 


"  Bull.  Soc.  chim.  France,  3d  series.  Vol.  XV,  p.  561, 1896. 
&Bull.  Soc.  min.  France,  Vol.  XIX,  p.  363, 1896. 


CLABKE  AND 
STEIGEB 


^_^~\    CONSTITUTION    OF    ANALCITE    AND   LEUCITE.  19 


that  is,  one-fourth  of  the  silica,  ought  to  be  set  free,  measurable  by 
extraction  with  sodium  carbonate  solution.  No  such  splitting  off 
occurs,  however.  An  ammonium  leueite  which  already  contained  1.97 
per  cent  of  soluble  silica  gave  only  1.70  per  cent  after  ignition ;  hence 
no  additional  silica  had  been  liberated.  We  may  conclude,  therefore, 
that  analcite  and  leueite  are  not  true  metasilicates,  but  pseudo-com- 
pounds, either  salts  of  a  polymer  of  metasilicic  acid  or  mixtures  of 
ortho-  and  trisilicates  analogous  to  those  which  we  find  among  the 
plagioelase  feldspars  and  in  the  mica  group. 

In  order  to  discuss  the  constitution  of  analcite,  let  us  recur  to  our 
analysis  of  the  variety  from  Nova  Scotia.  It  is  at  once  evident  from 
the  comparison  made  on  a  preceding  page  that  our  sample  of  the 
mineral  varies  notably  in  composition  from  the  requirements  of 
theory.  The  silica  is  2^  per  cent  too  high,  while  alumina  and  soda 
are  correspondingly  low.  No  probable  impuritj^  and  no  presumable 
errors  of  manipulation  can  account  for  so  great  a  divergence.  If  we 
consult  other  analyses,  as  we  find  them  tabulated  in  manuals  like 
those  of  Dana  and  Hintze,  we  shall  find  other  cases  resembling  this, 
and  also  examples  of  variation  in  the  opposite  direction,  with  silica 
low  and  an  apparent  excess  of  bases.  Most  analcite  gives  quite 
sharplj'  the  metasilicate  ratios  required  by  the  accepted  formula; 
but  the  variations  from  it  are  large  enough,  common  enough,  and 
regular  enough  to  command  attention.  The  analyses  are  not  all 
covered  bj^  the  recognized  theory,  and  the  apparent  irregularities  are 
not  fortuitous,  but  are  systematic  in  character. 

One  explanation  of  the  seeming  anomalies  is  simple  and  clear.  If 
analcite,  instead  of  being  a  metasilicate,  is  really  a  mixture  of  ortho 
and  trisilicate,  then  all  of  the  analyses  become  intelligible.  In  most 
cases  the  two  salts  are  commingled  in  the  normal  ratio  of  1:1,  but  in 
our  analcite  the  trisilicate  predominates,  while  in  some  other  samples 
the  ortho-salt  is  in  excess.     All  reduce  alike  to  the  simple  expression 

NaAlX.HgO, 

in  which  X  represents  nSi04+mSi308,  a  formula  which  agrees  with 
evidence  from  various  other  sources. 

For  example,  analcite  may  be  derived  in  nature  either  from  albite, 
AlNaSigOg,  or  nephelite,  AlNaSiO^,  and  on  the  other  hand  alterations 
of  it  into  feldspars  have  been  observed.  Its  closest  analogue,  leueite, 
has  yielded  pseudomorphs  of  orthoclase  and  elseolite,  while  leueite 
and  analcite  are  mutually  convertible  each  into  the  other.  The  evi- 
dence of  this  character — the  evidence  of  relationship  between  analcite 
and  other  species — is  varied  and  abundant,  and  the  simplest  conclusion 
to  be  drawn  from  it  is  that  which  ha;?  been  given.  Every  alteration, 
every  derivation,  every  variation  in  the  composition  of  analcite  points 
to  the  same  belief.  The  consistency  of  the  data  can  not  well  be 
denied. 


20 


ACTION    OF    AMMONIUM    CHLORIDE    ON    SILICATES.       [bull.  207. 


In  tlie  case  of  a  normal  analcite — that  is,  one  which  conforms  to  the 
usual  empirical  formula — the  expression  which  best  represents  these 
relations  is 

Al.Na,  (SiO,),  (SiaOg)^.  4H2O; 
and  leucite  is  the   corresponding  potassium   salt,   but  anhydrous. 
Structurally  this  is  comj)arable  with  the  formulae  of  garnet,  zunjdte, 
sodalite,  and  noselite,  all  of  which  are  isometric  in  crystallization. 
The  more  important  of  the  symbols  are  as  follows : 


Al- 


/ 


Si04  =  Ca 

/Ca 

-SiO,  =  Ca 


Al- 


Si04=Na2 

\ai-ci 

.SiCX=Na,  Al- 


Si04=Na2 

NA1-S04-Na 

-SiO,=Na, 


Al- 


Si04=Al 
Garnet. 

Si04=K.2 

\Al-si04: 

-Si.,(L=Ko 


Si04=Al 
Sodalite. 


:A1 


Al- 


\ 

Si04=Al 
Noselite. 

Si04=Na2 
/         NAl-Si04=Al 
— Si30s=Na2  +4H2O 


SigOg^Al 
.  Leucite. 


SigOg^Al 
Analcite. 


That  is,  analcite  and  leucite  become  members  of  the  garnet-sodalite 
group  of  minerals,  and  their  relations  to  nephelite,  albite,  etc.,  natural 
and  artificial,  are  perfectly  clear.  In  analcite  there  may  be  admix- 
tures of  strictly  analogous  ortho- or  trisilicate  molecules;  but  these 
remain  to  be  sex3arately  discovered.  The  ammonium  salt  correspond- 
ing to  such  a  mixture,  when  ignited,  might  be  expected  to  give  the 
following  reaction : 


Si04— Anig 

^Al-SigOgEEEEAl 


SiO. 


\ 


Al-SigOg^Al; 


Al Si()4  =  Ain2 


-2Am20=Al- 


-SiO, 


Si.,0«-^A1 


Si,0«=Al 


a  reaction  which  is  in  harmony  with  our  experimental  results.  In  it 
no  free  silica  appears;  and  manj'^,  if  not  all,  conditions  of  the  problem 
are  satisfied.  One  difficulty,  however,  stands  in  the  way  of  an  unqual- 
ified acceptance  of  these  formulae.  Garnet,  sodalite,  nephelite,  albite, 
etc.,  are  but  moderately  attacked  by  ammonium  chloride,  and  so  far 
have  yielded  no  definite  ammonium  derivatives.  Whether  this  dif- 
ference in  behavior  is  constitutional  or  not  it  is  hardly  possible  to 
say,  but  it  must  be  taken  into  account  in  connection  with  all  of  the 
other  evidence.     We  must  remember,  moreover,  that  the  formulae 


"YS/r""]  pollucite.  21 

are  not  ultimate  verities  to  be  blindly  accepted.  They  are  simply 
expressions  which  represent  composition  and  a  wide  i-ange  of  estab- 
lished relationships,  and  which  serve  a  distinct  purpose  in  tlie  coi-rela- 
tion  of  our  knowledge.  Properlj^  used,  with  due  recognition  of  their 
limitations,  they  are  helpful,  and  suggest  possibilities  of  research ; 
misused,  they  may  become  mischievous.  They  now  satisfy  most  of 
the  known  conditions,  and  that  is  a  sufficient  warrant  foi'  their 
existence. 

POLLUCITE. 

On  account  of  the  general  analogy  between  pollucite,  analcite,  and 
leucite,  the  first-named  species  of  the  three  seemed  to  deserve  some 
attention.  Through  the  kindness  of  Prof.  S.  L.  Penfield,  about  10 
grams  of  very  pure  material  from  Hebron,  Me.,  was  put  at  our  dis- 
posal, and  three  analyses  of  it  by  Wells  were  already  on  record.  ^^ 
The  average  of  these  analyses  is  as  follows : 

SiOa .....  43.53 

AI2O3 , 16.3'7 

CaO .22 

Na^O 1.81 

K2O . .49 

Li^O __.- .04 

CS2O 36.08 

HjO... 1.52 

100. 06 

Five  grams  of  the  finely  powdered  mineral  was  heated  in  a  sealed  tube 
with  four  times  its  weight  of  ammonium  chloride  to  350°  during  forty 
hours.  Upon  leaching  with  water  0.14  per  cent  of  CaO,  1.28  of 
NajO,  and  12.30  of  CsgO  were  extracted.  Probably  the  calcium 
chloride  formed  contained  some  potassium  chloride,  but  that  point 
was  ignored  as  irrelevant.  The  air-dried -residue  had  the  following 
composition : 

SiOa . ---  49.21 

AI2O3 18.32 

CaO . . none 

CsjOCKaO) 28.84 

NajO none 

NH3 2.52 

H2O 1.91 

100. 80 

The  high  summation  here  is  due  to  reckoning  some  KCl  as  CsCl. 
Of  the  silica  in  this  product  2.36  per  cent  was  soluble  in  the  standard 
solution  of  sodium  carbonate.  After  ignition,  4.13  ]3er  cent  was 
soluble.     Some  silica,  therefore,  was  split  off  bv  heating. 

a  Am.  Joiir.  Sci.,  3d  series,  Vol.  XLI,  p.  313, 1891. 


22  ACTION    OF    AMMONIUM    CHLORIDE    ON    SILICATES.       [bull.  207. 

In  a  second  experiment  one  gram  of  pollucite  was  heated  with 
ammonium  chloride  for  five  hours,  the  other  conditions  being  the 
same  as  before.  Upon  leaching,  11.55  per  cent  of  CsgO  was  extracted, 
and  a  partial  analysis  of  the  air-dried  residue  gave  the  following  data: 

SiO^ 47.87 

AlA 17.85 

NHg 2.83 

H2O 1.55 

Alkalies  (by  difference) 29.90 

100. 00 

The  two  products  were  evidently  the  same,  and  onlj^  about  one- 
third  of  the  alkalies  in  the  pollucite  had  been  extracted.  So,  also, 
the  ammonia  taken  up  was  only  about  one-third  of  that  which  was 
retained  by  analcite  and  leueite.  The  transformation,  then,  is 
merely  partial,  and  further  experimentation  seems  to  be  unnecessarj^, 
at  least  for  j)resent  purposes.  The  analogy  with  analcite  and  leueite 
is  far  from  perfect. 

NATROLITE. 

In  a  preliminary  experiment  upon  an  impure,  yellowish  natrolite 
from  Aussig  in  Bohemia,  we  found  that  this  species  was  peculiarly 
well  suited  to  reaction  with  ammonium  chloride.  By  heating  with 
the  reagent  in  a  sealed  tube  and  subsequent  leaching  with  water, 
17.56  per  cent  of  bases  was  extracted,  and  in  the  residue  8.29  per 
cent  of  ammonia  was  found.  Careful  work  upon  this  species  was 
therefore  desirable. 

The  material  available  for  our  experiments  came  from  the  well- 
known  locality  at  Bergen  Hill,  N.  J.,  and  consisted  of  a  mass  of 
slender  needles  densely  matted  together.  Part  of  the  uniform, 
ground  sample  was  analyzed,  with  fractional  determinations  of  the 
water,  and  part  was  used  for  the  sealed  tube  experiments,  precisely 
as  in  the  research  upon  analcite  and  leueite.  Three  of  these  experi- 
ments were  made,  and  in  each  case  the  natrolite  was  mixed  by  grind- 
ing in  an  agate  mortar  with  four  times  its  weight  of  dry  ammonium 
chloride,  after  which  it  was  heated  to  350°  in  the  sealed  tube.  Even 
during  the  grinding  a  slight  reaction  took  place,  and  a  distinct  smell 
of  ammonia  was  given  off  by  the  mixture.  With  pectolite  the  same 
smell  was  perceived.  The  three  experiments  may  be  summarized  as 
follows : 

A.  Heated  eleven  hours.  Upon  leaching,  14.89  per  cent  of  soda  and  1.20  of 
lime  were  extracted.     In  the  residue  9.26  per  cent  of  ammonia  was  found. 

B.  Heated  nine  hours.  Leach  not  examined.  9.26  of  ammonia  in  residue. 
The  complete  analysis  of  the  residue  is  given  farther  on. 

C.  Heated  three  hours.  14.09  per  cent  of  soda  and  0.20  of  lime  were  extracted. 
The  residue  contained  8.87  per  cent  of  ammonia.     In  this  instance  the  heating 


CLARKE  AND  "I 
STEIQBR.      J 


NATJROLITE. 


23 


was  relatively  brief,  in  order  to  learn  whether  its  duration  could  he  advanta- 
geously lessened.  The  reaction  was  evidently  less  complete  than  in  experiments 
A  and  B. 

In  the  subjoined  table  we  give  first  the  analysis  of  th(^  natrolite  itself, 
and  then  that  of  tlie  leaclied  residue  from  experiment  B.  In  tlie  latter 
we  found  that  0.86  per  cent  of  silica  Avas  soluble  in  sodium  carbonate 
solution,  and  that  soda  and  lime  remained  corresponding  to  4.01  per 
cent  of  the  original  mineral.  Deducting  these  impurities,  together  with 
the  0.42  per  cent  of  hygroscopic  water,  and  recalculating  to  100  per 
cent,  we  get  the  reduced  composition  of  the  residue.  In  the  last 
column  is  given  the  calculated  composition  of  an  anhydrous  ammonium- 
natrolite,  (NH4)2Al2Si30io.  This  compound  has  evidently  been  formed 
to  an  extent  represented  by  over  94  per  cent  of  the  leached  natrolite 
residue.  The  agreement  between  theor}^  and  even  the  unreduced 
analysis  is  practically  conclusive  on  this  point. 


Natrolite 
found. 

Residue 
found. 

Residue 
reduced. 

(NH4)2Al2 

SiaOio  cal- 
culated. 

SiO. 

AIA  .._ 

46.62 
26.04 

1.48 
none 
15.67 

53.  71 

29.94 

.34 

53.86 
30.52 

54.06 
30  43 

CaO :_  _           

K,0 , 

NajO 

.37 
9.26 

.42 
5.94 

NHs 

9.85 

10.14 

HjOatlOO' 

.39 

10.18 

B..fi  above  100° 

5.77 

5.37 

100. 38 

99.98 

100. 00 

100. 00 

The  fractional  water  determinations  will  be  given  later,  in  connec- 
tion with  similar  data  for  scolecite  (p.  25). 

It  ma,y  not  be  superfluous  to  note  that  the  Vt^ater  given  in  the  last 
two  columns  of  the  foregoing  table  represents  the  difference  between 
ammonia  and  the  hypothetical  ammonium  oxide  which  has  replaced 
soda. 

Two  other  experiments  upon  natrolite  remain  to  be  noticed.  First, 
the  fresh  mineral  was  boiled  for  fifteen  minutes  with  a  25  per  cent 
sodium  carbonate  solution;  0.72  per  cent  of  silica  dissolved.  Similar 
treatment  of  ignited  natrolite  took  out  0.62  per  cent.  No  silica  is 
split  off  by  ignition.  Ammonium  natrolite  before  ignition  yielded 
0.85  per  cent  of  soluble  silica,  and  after  ignition  0.86  per  cent.  Here 
again  no  silica  had  been  split  off  from  the  molecule,  and  practicallj^ 
none  was  liberated  by  the  action  of  the  ammonium  chloride  upon  the 
natrolite.  A  simple,  direct  substitution  of  ammonium  for  sodium 
had  occurred. 


24 


ACTION    OF    AMMONIUM    CHLORIDE    ON    SILICATES.       Lbull- 207. 


Heated  with  ammonium  chloride  in  an  open  crucible,  natrolile  gives 
only  a  partial  reaction.  This  is  shown  by  the  earlier  experiments  of 
Schneider  and  Clarke  upon  natrolite  from  Magnet  Cove,  Arkansas, 
from  which,  by  a  triple  heating  with  the  reagent,  onlj^  0.50  jier  cent 
of  soda  was  extracted  out  of  a  total  of  15.40. 

SCOLECITE. 

On  account  of  the  well-recognized  analogy  between  natrolite  and 
scolecite,  the  latter  mineral  seemed  to  be  peculiarly  worthy  of  exami- 
nation. The  specimen  at  our  disposal  was  a  mass  of  stout,  radiating 
needles,  which  was  collected  by  one  of  us  at  Whale  Cove,  on  the  island 
of  Grand  Manan,  New  Brunswick.  Scolecite,  we  believe,  has  not 
hitherto  been  recorded  from  this  locality,  and  on  this  account  alone 
the  material  deserved  attention. 

Three  sealed  tube  experiments  were  carried  out,  essentiallj^  as  in 
the  case  of  natrolite,  as  follows : 

A.  Heated  ten  hours  at  350°.  13.74  per  cent  of  lime  and  0.35  of  soda  were  taken 
out.     The  residue  contained  8.78  per  cent  of  ammonia. 

B.  Heated  ten  hours  at  370°.  13.97  of  lime  and  0.22  of  soda  were  extracted. 
8.48  per  cent  of  ammonia  in  the  residue.  On  account  of  the  excessive  temperature 
of  this  experiment,  some  reversion  of  the  converted  material  had  taken  place. 

C.  Heated  five  hours  at  340°-350°.  Leach  not  studied.  8.91  per  cent  of  ammonia 
in  residue. 

Analyses  of  the  scolecite  and  of  residues  B  and  C  are  given  below. 
The  less  perfect  transformation  in  the  case  of  B  is  evident. 


Scolecite. 

Residue  B. 

Residue  C. 

SiO., . 

Al,Oo 

45.86 

25.78 

13.92 

.41 

53.39 

30.  51 

.63 

undet. 

8.48 

.74 

6.38 

53.69 
30.50 

CaO 

Na^O 

NH,      _.     . 

.43 

.29 

8.91 

H^OatlOO".    -              _    _   _     

.40 
13. 65 

.12 

H^O  above  100° 

6.52 

100.02 

100. 03 

100.45 

The  product  of  the  reaction  is  plainly  the  same  as  that  obtained 
from  natrolite,  and  the  identity  in  type  of  the  two  species  is  perfectly 
clear.  This  fact  is  further  emphasized  by  an  experiment  upon  the 
solubility  of  silica.  The  fresh  scolecite  gave  up  0.36  per  cent  of  silica 
to  sodium  carbonate  solution,  and  the  ignited  mineral  yielded  only 
0.50  per  cent.     Again,  natrolite  and  scolecite  behave  in  the  same  way. 

Ui^on  both  minerals  fractional  determinations  of  the  water  were 
made,  and  the  amount  lost  at  each  temperature  was  noted.     The 


CLARK 
STEIGER 


CE  AND"! 
IGER.      J 


SOOLECITE. 


25 


results,  expressed   in   percentages  of  tli(^  original   minerals,  were  as 
follows : 


Temperature. 

Water  lost. 

Natrolite. 

Scolecite. 

100°-           ---    

0.39 
.40 

•  37 
8.51 
.72 
.12 
.06 

10. 57 

0.40 

180°                  - 

.52 

250°                                       -         -               .    _   ...    

4.76 

350°                      - 

.  55 

Incipient  redness 

Full  redness 

Over  blast                   -  -   -  -                -  -     ^                 _  _   ^     _ 

7.72 
.04 
.06 

14.05 

Scolecite  contains  one  more  molecule  of  water  than  natrolite,  and 
that  amount,  one-third  of  its  total,  seems  to  go  off  at  a  lower  temper- 
ature than  the  other  two  molecules.  Otherwise  the  two  series  of  ex- 
periments are  probably  not  far  apart,  and  they  indicate  that  the  water 
is  in  neither  case  constitutional.  The  same  conclusion  is  suggested 
by  the  existence  of  the  anhydrous  ammonium  compound,  the  three 
formulae  being  as  follows: 

Scolecite CaAl^SisOio.  SH^O 

Natrolite Na^Al.SigOio.  2H,0 

Ammoninm  natrolite (NH4)2Al2Si30io 

The  parallelism  is  complete ;  and  all  three  compounds  are  evidently 
salts  of  an  acid,  HgSigOio,  which  is  probably  orthotrisilicic  acid, 
Si302(OH)8.  The  relations  of  this  acid  to  its  anhydrides  will  be  con- 
sidered later. 

PREHNITE. 

In  a  former  bulletin  upon  the  constitution  of  the  silicates, "  one  of 
us  attempted  to  show  that  natrolite,  scolecite,  and  prehnite  were 
similar  in  chemical  structure,  provided  that  all  or  part  of  their  water 
was  regarded  as  constitutional.  The  formulae  then  assigned  were  as 
follows : 

Scolecite : - Al2(SiOj3CaH,.  H.O 

Natrolite - AI,  ( SiQi )  sNa^H^ 

Prehnite Al2(SiOj3Ca2H2 

Two  of  these  formulae  must  now  be  abandoned,  because  of  the  exper- 
imental evidence  which  we  have  obtained,  but  the  prehnite  remains 
to  be  considered. 

fl  Clarke,  F.  W.,  Bull.  U.  S.  Geol.  Survey  No.  125,  p.  45,1895. 


26  ACTION    OF    AMMONIUM   CHLOKIDE    ON    SILICATES.       [bull.  207. 

The  material  chosen  for  examination  was  an  old  specimen  of  preh- 
nite  from  Paterson,  N.  J.  The  analysis  of  it,  with  fractional  water 
determinations,  is  given  below : 

SiOj 42.31 

AI2O3 - 19.95 

Fejps 6.20 

PeO none 

CaO 36.68 

H^O 5.02 

100. 11 

Fractional  water. 

At  100° 0.21 

At  180° , - .18 

At  250° .10 

At  350° .11 

Incipient  red  lieat .28 

Full  red  heat 4.05 

Over  blast ^ .09 

5.02 

With  sodium  carbonate  snlution,  0.38  per  cent  of  silica  was  ex- 
tracted from  the  fresh  mineral.  From  the  ignited  prehnite,  1.22  per 
cent  was  taken  out.  Very  little  silica,  therefore,  is  liberated  by  ignition. 

Two  determinations  were  made  of  the  action  of  ammonium  chloride, 
as  follows : 

A.  Heated  eight  hours.  On  leaching  with  water,  1.31  per  cent  of  lime  and  0.17 
of  alumina  dissolved. 

B.  Heated  twelve  hours.  1.41  per  cent  of  lime  was  extracted,  and  in  the  washed 
residue  0.22  per  cent  of  ammonia  was  foiind. 

Prehnite,  therefore,  differs  widely  from  natrolite  and  scolecite  in 
its  behavior  with  ammonium  chloride.  Very  little  action  takes  place, 
even  upon  long  heating  to  350°  in  a  sealed  tube,  and  practically  no 
ammonia  is  absorbed.  The  water  is  more  firmly  held  than  was  the 
case  with  the  other  two  minerals,  and  is  almost  certainly  to  be  regarded 
as  constitutional.  The  orthosilicate  formula  for  prehnite  is  unaf- 
fected by  these  results,  and  may  stand  as  fairly  probable.  Prehnite 
can  not  be  correlated  with  natrolite  and  scolecite  on  any  basis  of 
similar  chemical  structure. 


THE  TRISILICIC   ACIDS. 

We  have  already  shown  that  natrolite  and  scolecite  are  probably 
salts  of  an  orthotrisilicic  acid,  HgSgOio,  '^^  ^^id  which  is  not  particu- 
larly well  known.  As  it  has  interesting  relations  to  other  compounds, 
some  discussion  of  its  constitution  and  its  derivatives  may  not  be  out 
of  place  here. 

The  general  theory  of  the  silicic  acids  is  extremely  simple.  Silicon 
being  a  quadrivalent  element,  its  normal  acid,  the  orthosilicic,  is 


'^^STEWER^^]  THE    TRISILICIO    ACIDS.  27 

81(011)4.     From  this,  by  successively  eliiuinatinjj;    two  inoleciiles  of 
water,  two  anhydrides  may  be  derived,  thus: 

Orthosilicic  acid Si(0H)4 

First  anhydride,  metasilicic  acid 0=Si^^(OH)^ 

Second  anhydride,  silicon  dioxide - .  0=Si=^0 

These  acids,  containing  one  atom  of  silicon  each,  may  be  called  the 
monoslllclc  acids,  and  some  of  their  salts  are  perfectly  well  known. 
Olivine  and  anorthlte,  for  Instance,  are  orthosllicates,  while  the  true 
metasillcates  are  represented  by  talc  and  pectollte.  The  evidence  in 
the  case  of  the  last-named  mineral  will  be  presented  later. 

When  two  molecules  of  orthosilicic  acid  coalesce,  with  elimination 
of  water,  an  orthodlsUlcic  acid  is  formed,  and  this  is  the  first  member 
of  another  series,  as  follows: 

Si=(OH)s  Si=(0H)3  0=Si-OH 

o  00 

Si=(0H)3  0=Si-OH  0=Si-OH 

Orthodisilicic  acid.  Metadisilicic  acid.  Pyrosilicic  acid. 

To  the  first  and  third  of  these  acids  various  minerals  correspond. 
The  second  acid,  however,  is  a  polymer  of  metasilicic  acid,  but  differs 
from  the  latter  In  its  possible  derivatives.  When  an  acid  metasillcate 
is  heated  silica  is  set  free,  but  in  the  case  of  a  metadislllcate  this 
would  not  necessarily  occur.  Possibly  leucite  and  analcite  maj^  be 
metadlsillcates,  although  the  evidence  so  far  presented  does  not  sup- 
port this  view.  The  possibility,  however,  we  are  compelled  to  recog- 
nize as  one  which  might  ultimately  be  verified. 

With  the  coalescence  of  three  orthosilicic  molecules  a  series  of  trisi- 
liclc  acids  begins,  and  one  of  these  forms  salts — the  feldspars — which 
are  the  most  abundant  compounds  existing  in  the  mineral  kingdom. 
The  acids  of  the  series  are  these : 

Si=(0H)3  Si=(0H)8  Si=(OH)s  0=Si-OH 

o  000 

Si=(0H)2  Si=0  Si=0  Si=0 

'       O  .0  O  O 


Si=(OH)3  Si=(0H)3  0=Si-OH  0=Si-OH 

Orthotrisilicic  acid.      Metatrisilicic  acid.      Trisilicic  acid.      Third  anhydride. 


28  ACTION    OF    AMMONIUM    CHLORIDE    ON    SILICATES.       [bull.  207. 

The  third  anhydride  represents  an  acid  to  which  no  known  salts 
correspond.  One  step  further  and  we  have  a  fourth  anhydride,  SigOg, 
or  empirically  SiOg,  which  may  or  may  not  be  the  true  formula  of 
quartz.  Quartz  is  undoubtedly  a  polymer  of  SiOj;  its  most  frequent 
associates  are  trisilicates — the  feldspars — and  hence  the  formula  SigOg 
has  a  certain  degree  of  plausibility.  This  suggestion,  however,  is 
purelj^  si3eculative  and  has  no  definite  scientific  value.  Its  validity 
would  be  most  difficult  to  establish. 

From  the  first  of  these  trisilicic  acids  natrolite  and  scolecite  appear 
to  be  derived.  If  we  ignore  the  "zeolitic  water,"  which  is  not  a  part 
of  the  essential  silicate  molecule,  the  two  compounds  may  be  formu- 
lated thus: 

Si  =  03  =  Al  Si  =  03  =  Al 

o  o 

Si  =  02  =  Na2  Si  =  02  =  Ca 

o  o 

Si^Og^Al  Si  =  03  =  Al 

Natrolite.  Scolecite. 

So  far,  no  other  salts  of  this  acid  have  been  clearly  identified. 

The  second  acid  of  the  series,  like  the  second  of  the  disilicic  acids, 
is  a  polymer  of  the  ordinary  metasilicic  compound.  It  is  well  under- 
stood that  many  so-called  metasilicates  are  not  representatives  of  the 
simple  acid  HgSi  O3 ;  some  of  them  are  mixtures  of  orthosilicates  with 
salts  of  the  third  acid  in  this  group,  H4  SigOg;  others  may  be  derived 
from  j)olymers  like  that  which  is  now  under  consideration.  For 
example,  anhydrous  analcite  and  jadeite  are  both  represented  by  the 
empirical  formula  NaAlSigOg,  but  they  differ  widely  in  densitj^  in 
solubility,  and  doubtless  also  in  crystalline  form.  One  molecule, 
then,  is  much  more  condensed  than  the  other.  If  analcite  should 
prove  to  l)e  a  metadisilicate,  then  jadeite  may  be  its  equivalent  in  the 
trisilicic  series,  or  it  may  belong  with  some  still  higher  polj^mer.  The 
possibilities  are  many,  but  to  establish  au}^  one  of  them  by  proof 
would  demand  more  evidence  than  is  yet  in  our  possession. 

The  third  member  of  the  trisilicic  series  is  the  most  important  of 
all,  for  among  its  salts  are  the  two  feldspars,  albite  and  orthoclase, 
which  together  make  up  fully  one-half  of  the  solid  crust  of  the  earth. 
It  is  also  noteworthy  from  the  fact  that  its  formula  can  be  so  written 


CLARKE  AND 
STElGEll 


^°]  STILBITE.  29 


Sis 

1 

=  (OH), 

O 

Si= 

=o 

0 

0  = 

=  Si- 

-OH 

as  to  represent  two  isoinei'ic  forms,  to  wliicli  distinct  salts  prol)Hl)ly 
correspond.     The  two  formulsB  are  as  follows: 

0=Si  — OH 
O 

and  Si  =  -(0H)2 

O 

0  =  Si  — OH; 

and  their  significance  is  clear  when  we  remember  that  the  ordinary 
trisilicates  are  commonly  dimorphous.  Thus  we  have  orthoclase  and 
soda  orthoclase,  monoclinic;  and  albite  and  microcline  triclinic;  one 
pair  perhaps  belonging  to  one  isomer,  the  other  to  the  other.  The 
rare  minerals  eudidymite  and  epididymite,  which  are  also  isomeric 
trisilicates,  further  illustrate  the  same  conception;  but  we  can  not  as 
yet  assign  either  compound  distinctly  to  either  formula. 

By  an  extension  of  the  process  herein  developed,  which  is  by  no 
means  new,  higher  polj^silicic  series  may  be  formulated.  Since,  how- 
ever, such  acids  correspond  to  no  definitely  known  salts,  to  write  their 
formulae  would  be  a  useless  exercise  of  the  imagination.  Beyond  the 
trisilicic  acids  we  enter  the  region  of  the  unknown. 

STILBITE. 

The  specimen  selected  for  study  was  a  nearly  white,  typical  exam- 
ple from  Wassons  Bluff,  Nova  Scotia.  The  analysis  and  the  fractional 
water  determinations  were  as  follows: 

Si02_. - 55.41 

AI2O3 16.85 

FeA .18 

MgO .05 

CaO ■ 7.78 

Na^O 1.33 

H2O 19.01 

100.51 
Fractional  ivater. 

At  100° . 3.60  ■ 

At  180° 6.46 

At  250° 3.80 

At  350° 3.10 

Low  redness 3. 95 

Fnll  redness .06 

Over  blast .04 

19.01 


30 


ACTION    OF    AMMONIUM    CHLORIDE    ON    SILICATES.       [bull.  207. 


On  boiling  with  sodium  carbonate,  1.37  per  cent  of  silica  went  into 
solution.  After  ignition,  only  1.03  per  cent  was  obtained.  No  silica, 
therefore,  is  split  off  when  stilbite  is  ignited.  If  the  mineral  were  a 
hydrous  acid  metasilicate,  H4CaAl2Si60i8.4H20,  as  has  been  assumed 
by  some  authorities,  one-third  of  the  silica  should  have  been  set  free. 
Hence  the  metasilicate  formula  is  to  be  regarded  as  unsatisfactory. 
The  evidence  here  presented  counts  for  something  against  it. 

Two  samples  of  the  ammonium  chloride  derivative  were  prepared. 
In  leaching  with  water  the  insoluble  residue  was  washed  until  the  wash- 
ings gave  no  reaction  for  chlorine.  The  chlorine  shown  in  the  sub- 
joined analyses  is,  therefore,  present  in  an  insoluble  form  and  not  as 
adhering  ammonium  chloride.  Dried  at  50°  the  two  products  gave 
the  following  comi30sition : 


A. 

B. 

SiOj         '._.:.... .. 

60.80 
18.36 

1.86 
.08 

5.12 
12. 96 

1.31 

60.67 

ALOo       -- 

18.25 

CaO       -     

1.46 

Na,0 

.15 

NHg 

5.13 

H20 

13.91 

CI : '. 

1.04 

Less  0 

100. 49 
.29 

100.61 
.23 

100. 20 

100.38 

Sample  B  was  further  examined  as  to  the  presence  of  soluble  silica, 
and  1.52  per  cent  was  found.  After  ignition,  only  1.62  per  cent  went 
into  solution.  These  results  conform  to  those  obtained  with  the  orig- 
inal stilbite,  and  tend  to  show  that  the  ammonium  derivative  is  a  com- 
pound of  the  same  order.  In  the  case  of  the  unignited  substance  the 
residue  remaining  after  the  removal  of  soluble  silica  was  thoroughly 
washed,  and  then  examined  for  alkali.  It  was  found  to  contain  9.30 
per  cent  of  soda,  which  shows  that  the  ammonium  salt  had  been  trans- 
formed back  into  the  corresponding  sodium  compound. 

From  the  foregoing  facts  it  is  clear  that  stilbite,  like  the  zeolites 
previously  studied,  is  converted  by  the  action  of  ammonium  chloride 
into  an  ammonium  salt.  That  is,  sodium  and  calcium  are  removed 
as  chlorides,  ammonium  taking  their  place  to  form  ammonium  stilbite. 
The  reaction,  however,  is  less  complete  than  it  was  in  the  cases  of 
analcite  and  natrolite,  but  whether  this  is  due  to  a  greater  stability  of 
the  stilbite  molecule  or  only  to  a  different  degree  of  fineness  in  the 
powder  upon  which  the  operations  were  performed,  we  can  not  say. 
Neither  have  we  any  explanation  to  offer  of  the  retention  of  chlorine 


CLARKE  AND 
STEIGKR 


]  STILBITE    AND    HEULANDITE.  31 


by  the  ammonium  derivative.  Althougli  the  amount  of  chlorine  is 
small,  it  needs  to  be  accounted  for. 

If  we  discuss  the  comj)osition  of  the  stilbite  and  of  its  ammonium 
derivative,  the  relations  between  them  become  very  clear.  Nej^lect- 
ing  the  water  as  "zeolitic,"  to  use  Friedel's  phrase,  and,  therefore, 
as  not  a  part  of  the  chemical  molecule,  and  also  rejecting  the  1.37  per 
cent  of  soluble  silica  as  iprobably  an  impurity,  the  ratios  derived  from 
the  anal^^sis  give  this  empirical  formula  for  the  mineral: 

Na4oCai4oAl332Si9ot0246„. 
This  corresponds  to  a  mixture  of  ortho-  and  trisilicates  in  which 
SigOgiSiO^::  286:  43;  and  uniting  these  radicles  under  the  indiscrimi- 
nate symbol  X,  we  have,  as  a  more  general  expression, 

NajoCai.jo  AlggaXggy ; 
or  combining  monoxide  bases, 

which  is  essentially  R"Al2X2.  Since  the  Si04  groups  are  practically 
equal  in  number  to  the  sodium  atoms,  the  stilbite  is  probably  a  mix- 
ture, very  nearly,  of  ]SraAlSi04  and  CaAl2(Si30g)2  in  the  ratio  of  1 : 7 
This  is  in  accordance  witli  the  well-known  theory  of  Fresenius  as  to  the 
constitution  of  the  iDhillipsite  group,  to  which  stilbite  belongs.  Stilbite 
is  mainly  a  hj^drous  calcium  albite,  commingled  with  varying  amounts 
of  corresponding  orthosilicates  of  soda  and  lime. 

For  the  ammonium  derivative  similar  relations  hold.    Taking  analy- 
sis "B"  for  discussion,  rejecting  soluble  silica  and  chlorine  as  impu- 
rities, and  neglecting  all  water  except  that  which  belongs  to  the  suj)- 
posable  ammonium  oxide,  the  ratios  give  this  formula: 
(NH4)3oiNa4Ca2gAl358Si9>^502684. 

Uniting  sodium  and  calcium  with  ammonium,  this  becomes 

R''357^^358(^i3<^8)314(Si04)43 ; 

or,  more  generally, 

^  357-^1358-^3575  =1:1:1- 

The  derivative,  therefore,  is  a  compound  of  the  same  order  as  the 
original  stilbite,  with  the  ratio  of  1:  7  still  holding  between  the  ortho 
and  trisilicate  groups.  This  conclusion,  however,  ignores  the  pres- 
ence of  chlorine,  and  is,  therefore,  inexact  to  some  extent.  We  are 
not  dealing  with  ideall}^  pure  compounds. 

HEULANDITE. 

Pure,  white  heulandite  from  Berufiord,  Iceland,  was  the  material 
taken  for  investigation.  Upon  boiling  with  sodium  carbonate,  1.73 
per  cent  of  silica  went  into  solution.  From  previously  ignited  heu- 
landite, only  1.14  per  cent  was  extracted.  No  silica,  therefore,  was 
liberated  upon  ignition,  and  a  hydrous  metasilicate  formula  for  the 
mineral  seems  to  be  improbable.     Only  one  lot  of  the  ammonium 


32 


ACTION    OF    AMMONIUM    CHLORIDE    ON    SILICATES.       [bull.  207. 


chloride  derivative  was  prepared,  and  its  composition,  together  with 
that  of  the  henlandite,  is  given  below. 


Heulandite. 

Ammoninm 
salt. 

SiO.^ 

rfi.  10 

16.82 
.07 

6.95 
.46 

1.25 
.43 

} 
} 

61.24 

AI2O3 

MgO 

CaO                                                         -        ----- 

18. 00 
2.56 

SrO 

Na^O  -           .--.    

K2O                        

.60 

NH3                             -       -        

4.42 

H2O  at  100°                   .  -                       -       - -- 

3.61 
13.00 

H2O  above  100° 

13.63 

- 

99. 68 

100. 45 

Here,  again,  we  have  the  same  kind  of  transformation  as  before, 
but  rather  less  complete  than  in  the  case  of  stilbite.  That  the  ammo- 
nium taken  up  is  equivalent  to  the  bases  removed  is  shown  by  a  study 
of  the  ratios.  Ignoring  water  and  the  soluble  silica,  the  heulandilc 
ratios  are  as  follows : 

^  48-'^    ISO-^-'-SSO^^ 923^2495? 

or,  uniting  bases, 

I^"l54Al33o(Si308)goo(Si04)24. 

Again  simplifying,  this  becomes 

^    154-^^330-^3245 

or  very  nearly  1:2:2,  as  in  stilbite. 

Similarly  discussed,  the  ammonium  salt  gives  the  ratios 

K  27QUa4gAlgg2blio2iOa74g, 

equivalent  to 

'  ^'362^1353X353,  or  1 :  1 : 1. 

In  both  cases  the  orthosilicate  molecules  are  few,  and  the  com- 
pounds approximate  to  trisilicates  very  closely. 

CHABAZITE. 

Characteristic  flesh-colored  crystals  from  Wassons  Bluif,  Nova 
Scotia.     The  analysis  and  fractional  water  determinations  are — 

SiOa 50.78 

AI2O3 .-__---._     17.18 

Fe^Os .40 

MgO .04 

CaO 7.84 

Na^O 1.28  • 

K,0 . .73 

H,0 . 21.85 

100. 10 


'"'^s^iGElf'']  CHABAZITE.  33 

Fractional  water. 

At  100° 5.22 

At  180° :_. 5.70 

At  250° 3. 92 

At  350° 2. 36 

Low  redness 4. 51 

Full  redness .13 

Over  blast .01 

21.85 

The  unignited  mineral,  upon  boiling  with  sodium  carbonate,  gave 
0.86  per  cent  of  soluble  silica.  After  ignition  only  0.53  per  cent  was 
soluble.  Here  again  no  silica  is  liberated  b.y  calcination,  and  metasili- 
cate  formulae  may  be  disregarded. 

Two  samples  of  the  ammonium  chloride  derivative  were  prepared, 
which  after  thorough  washing  were  dried  at  40°  to  50°.  As  in  the 
case  of  stilbite,  small  quantities  of  chlorine  appear  in  the  compound, 
not  removable  by  washing.  The  amount  of  change  effected  is  also 
somewhat  less  than  with  stilbite,  and  about  the  same  as  with  heuland- 
ite.  The  analyses  of  the  two  samples  are  subjoined,  with  the  remain- 
ing alkali  all  reckoned  as  soda: 


A. 


B. 


SiO, 

AlA  -.... 

CaO 

Na,0(K,0) 

NH3 

H2O 

CI 

Less  O 


55.88 

56.09 

19.15 

19.49 

2.25 

2.01 

.35 

.24 

4.64 

4.83 

16.57 

16.01 

.95 

1.35 

99.79 

100. 02 

.21 

.30 

).58 


99.72 


In  B,  1.50  per  cent  of  soluble  silica  was  found.  After  ignition  this 
was  reduced  to  1.12  per  cent.  No  liberation  of  silica  accompanies  the 
splitting  off  of  water  and  ammonia. 

Upon  studying  the  molecular  ratios  for  chabazite  and  its  derivative, 
relations  appear  precisely  like  those  found  for  stilbite  and  heulandite. 
For  chabazite  itself,  rejecting  water  and  the  0.86  per  cent  of  soluble 
silica,  we  have 

^  58^%4lAl34o!5l832v)2344J 

or,  consolidating  soda  with  lime, 

Cai7oAl34o(Si308)246(S104)94. 


9506— Ko.  ^07—02- 


34 


ACTION    OF    AMMONIUM    CHLORIDE    ON    SILICATES.       [bull. 207. 


One  step  further  and  this  becomes 

Cai7oAl34QX34o=l :  2:  2. 
Treating  derivative  "B  "  m  tlie  same  way,  and  ignoring  chlorine  9S 
an  unexplained  impurity,  the  analysis  gives 

(NH4)284Na8Ca35Al383(Si308)266(Si04)ii2; 
or,  consolidating  bases  as  before, 

^^'362^82X378=1 : 1 : 1  nearly. 
The  assumption  of  commingled  ortho-  and  trisilicate  molecules  con- 
forms to  Streng's  theory  of  the  constitution  of  chabazite. 

THOMSONITE. 


The  compact-fibrous  variety  from  Table  Mountain,  near  Golden, 
Colo.     Analytical  data  as  follows : 

SiOa 41.13 

AI2O3 29.58 

CaO 11.25 

NaaO 5.31 

H2O ■ 13.13 

100.40 
Fractional  water. 

At  100° 1.01 

At  180° 1.44 

At  250° 1-05 

At  350° 3.90 

Low  redness 5. 65 

Over  blast .08 

13.13 

Before  ignition  the  mineral  yielded  0.45  per  cent  of  silica  to  sodium 
carbonate  solution.  After  ignition  0.68  per  cent  was  soluble.  The 
difference  is  trifling. 

Two  samples  of  the  ammonium  chloride  derivative  were  prepared. 
In  A  the  heating  was  only  to  300°,  in  B  to  350°.  Analyses  of  the 
leached  products  gave  the  following  results: 


A. 

B. 

SiOa 

42.41 
30.  50 
10.00 
2.63 
2.45 
11.96 

42.65 

A1,0, 

31.34 

CaO . 

9.23 

NaaO 

2.48 

NH3 ._     _... 

2.67 

H2O .- 

11.81 

99.95 

100.18 

CLAUKE  AND] 
STEIGER 


]  TH0M80NITE    AND    L A  UMONTITE.  35 


In  A,  1.80  per  cent  of  solnble  silica  was  found. 

In  this  case  tlie  amount  of  change  is  very  much  less  than  witli  the 
zeolites  previously  examined.  Little  lime  was  removed,  and  only 
about  half  of  the  soda.  Both  samples  were  prepared  with  six  hours 
of  heating  in  the  sealed  tube,  and  it  seemed  to  be  desirable  to  deter- 
mine whether  a  more  prolonged  treatment  would  produce  any  greater 
effect.  Accordingly  a  third  lot  of  thomsonite  was  mixed  with  ammo- 
nium chloride  and  heated  in  a  sealed  tube  to  350°  for  twenty-four 
hours.  The  leached  product  contained  3.40  per  cent  of  ammonia,  a 
distinct  increase  over  the  other  findings,  although  the  amount  of  trans- 
formation into  an  ammonium  salt  was  still  only  moderate. 

We  have  already  seen  that  stilbite,  heulandite,  and  chabazite 
approximate  more  or  less  nearly  to  trisilicates  in  their  composition. 
Thomsonite,  however,  is  essentially  an  orthosilicate,  with  variable 
admixtures  of  trisilicate  molecules.  In  the  example  under  considera- 
tion, ignoring  water  and  soluble  silica,  the  molecular  ratios  give  this 
formula : 

Nai72Ca2oiAl58o(Si308)5o(Si04)g28; 
or,  condensing, 

^    287^1580-^578  =  1  ^  2  :  2. 

Here  the  acid  radicles  are  ten-elevenths  orthosilicate.  Ammonium 
derivative  A,  similarly  computed,  gives  first — 

(NH4)i4,Na84Cai78Alg98(Si308)4i  (8104)55,; 

or,  uniting  univalent  bases  with  lime, 

^  292-^-'^598-^595=^l  ^  2  :  2; 
the  fundamental  ratios  being  practically  unchanged. 

It  will  be  observed  that  in  all  of  these  computations  of  formulae  we 
have  assumed  that  all  the  water  is  "zeolitic;"  that  is,  independent 
of  the  true  chemical  molecules.  This  question,  however,  needs  to  be 
separately  investigated  for  each  individual  species.  While  the 
assumption  is  valid  for  some  of  these  minerals,  it  is  not  necessarily 
valid  for  all.  The  real  chemical  differences  between  the  zeolites  are 
3^et  to  be  determined;  our  work  merely  proves  that  ammonium  com- 
pounds are  formed,  completely  in  some  cases,  i?artially  in  ethers. 
The  research  should  be  extended  to  cover  all  the  zeolites;  but  this 
task  we  must  leave  to  other  investigators. 

LAUMONTITE. 

Upon  this  species  only  one  rather  crude  experiment  has  been  tried, 
and  that  upon  material  of  unknown  origin.  The  mineral  was  heated 
with  ammonium  chloride  in  a  sealed  tube  as  usual,  and  then  leached 
with  water.  4.51  per  cent  of  lime  and  0.35  of  soda  were  extracted, 
and  in  the  residue  3. 95  per  cent  of  ammonia  was  found.  Laumontite, 
therefore,  behaves  much  like  the  other  zeolites,  and  is  only  partially 
transformed  into  an  ammonium  compound. 


36  ACTION    OF    AMMONIUM    CHLORIDE    ON    SILICATES.       [bull.  207. 

PECTOLITE. 

The  pectolite  whicli  was  chosen  for  examination  was  the  well-known 
radiated  variety  from  Bergen  Hill,  N.  J.  The  mineral  was  in  long 
white  needles,  and  apparently  quite  pure,  but  the  analysis  shows 
that  it  contained  some  carbonate  as  an  impurity.  Enough  of  the 
material  was  ground  up  to  furnish  a  uniform  sample  for  the  entire 
seiries  of  experiments,  and  the  work  properly  began  with  a  complete 
analysis.     The  results  obtained  are  as  follows : 

SiO^ 53.34 

AI2O3 .33 

CaO 33.33 

MnO .45 

Na^O 9.11 

H,0 2.97 

CO, - 67 

100. 10 
Fractional  ivater. 

At  105° - 0.27 

At  180° .16 

At  300° .22 

At  redness 2. 32 

2.97 
All  of  the  water  was  given  of£  at  a  barely  visible  red  heat,  and  the 
figures  show  that  practically  all  of  it  is  constitutional — a  fact  which 
perhaps  hardlj^  needed  reverification.    The  analysis  gives  the  accepted 
formula  for  pectolite, 

HNaCagSigOg. 
Does  this  I'epresent,  as  is  commonly  assumed,  a  true  metasilicate? 
If  it  does,  we  should  expect  that  ignition  would  split  off  silica  pro- 
portional to  the  acid  hydrogen,  or  one-sixth  of  the  total  amount.  To 
answer  this  question  several  portions  of  the  pectolite  were  sharply 
ignited,  to  complete  dehydration,  and  then  boiled  each  for  fifteen 
minutes  with  a  solution  of  sodium  carbonate  containing  250  grams  to 
the  liter.  In  the  extract  so  obtained  the  silica  was  determined,  and 
the  three  experiments  gave  the  following  percentages : 

8.96 
8.67 
8.42 

Mean,  8.68 

One-sixth  of  the  total  silica  is  8.89  per  cent,  and  the  experiments, 
therefore,  justify  the  original  expectation.  The  belief  that  pectolite 
is  a  metasilicate  is  effectively  confirmed. 

Upon  the  unignited  pectolite  the  sodium  carbonate  solution  has  a 
slow  decomposing  action,  both  silica  and  bases  being  withdrawn.  In 
two  experiments  fifteen  minutes  of  boiling  extracted  2.07  and  2.55 
per  cent  of  silica,  and  by  a  treatment  lasting  four  days  4.80  per  cent 


CLARtlE  ASD"] 
STEIGER.      J 


PECTOLITE. 


37 


was  taken  out.  With  water  alone  similar  results  were  obtained,  the 
action  being  so  rapid,  although  relatively  slight,  that  pectolite, 
moistened,  gives  an  immediate  and  deep  coloration  with  phenol 
phthalein.  By  boiling  the  powdered  pectolite  with  distilled  water 
alone,  1.G5  per  cent  of  silica  was  brought  into  solution,  and  the 
ignited  mineral,  similarly  treated  for  fifteen  minutes,  gave  1.78  per 
cent.  The  extraction  in  these  cases  is  really  an  extraction  of  alkaline 
silicate,  as  the  two  following  experiments  prove.  In  A  the  unignited 
pectolite  was  boiled  for  fourteen  hours  with  distilled  water,  and  in 
B  the  mineral  after  ignition  was  subjected  to  like  treatment  for  four 
hours.  The  dissolved  matter  in  each  case  was  determined,  with  the 
subjoined  results: 


Extracted. 

A. 

B. 

SiOa . 

2.98 

;30 

.81 

3  03 

CaO 

10 

Na^O  

1.50 

4.09 

4.63 

In  A  no  simple  ratio  appears,  but  in  B  the  extracted  silicate  approxi- 
mates very  nearly  to  the  salt  NaaSigOg.  In  each  instance  the  ratios 
vary  widely  from  those  of  the  original  mineral,  showing  that  actual 
decomposition  and  not  a  solution  of  the  pectolite,  as  such,  has  occurred. 

Schneider  and  Clarke/*  in  their  first  experiments  upon  the  ammo- 
nium chloride  reaction,  treated  pectolite  from  Bergen  Hill  three 
times  successively  with  the  reagent  and  then  leached  out  with  water. 
In  the  solution  20.50  per  cent  of  lime  and  6.95  of  soda  were  found, 
showing  that  a  very  considerable  decomposition  had  taken  place, 
but  the  residue  was  not  examined.  In  a  preliminary  experiment 
by  the  sealed  tube  method  we  found  that  20.72  per  cent  of  lime  and 
6.46  of  soda  were  taken  out,  while  i.44  per  cent  of  ammonia  was 
retained  by  the  residue.  That  is,  two-thirds  of  the  bases,  approxi- 
mately, had  been  converted  into  chlorides  by  the  reaction.  The  open 
crucible  and  the  sealed  tube  gave  essentially  the  same  results,  although 
the  retention  of  ammonia  was  not  noticed  by  Schneider  and  Clarke. 

In  order  to  obtain  further  light  upon  pectolite  we  continued  our 
experiments  with  the  sealed  tube  method,  and  have  obtained  very 
variable  results.  All  of  the  heatings  with  ammonium  chloride  were 
conducted  at  350°,  and  the  pectolite  used  was  from  the  same  Bergen 
Hill  specimen  wTiich  served  us  for  our  previous  work.  Our  data  are 
as  follows,  including  for  convenience  of  comparison  the  preliminary 
experiment  which  was  cited  above: 

A.  Heated  six  hours.  On  leaching,  20.72  per  cent  of  lime,  6.46  soda,  and  0.11 
alumina  dissolved.     The  residue  contained  1.44  per  cent  of  ammonia. 

a  Bull.  U.  S.  Geol.  Survey  No.  113,  p.  34,1893. 


38 


ACTION    OF    AMMONIUM    CHLORIDE    ON    SILICATES.       [bdll.  207. 


B.  Heated  six  hours.  20.10  per  cent  lime  and  5.80  of  soda  extracted.  1.45  per 
cent  ammonia  in  the  residue.  The  residue  was  also  examined  for  silica  soluble 
in  25  per  cent  sodiiim  carbonate  solution  (on  fifteen  minutes  boiling) ,  and  43.38 
per  cent  was  found. 

C.  Heated  six  hours.  Soluble  portion  neglected.  The  residue  contained  2.23 
per  cent  of  ammonia  and  61.79  per  cent  of  soluble  silica.  The  full  analysis  of 
this  residue  is  given  later. 

D.  Heated  ten  hours.  A  complex  breaking  up  of  the  pectolite  took  place,  and 
leaching  with  water  extracted  the  following  percentages: 

SiOa 5.43 

AI2O3 .22 

CaO 28.20 

MnO .23 

Na^O 8.29 

The  residue  from  this  leaching  contained  39.63  of  soluble  silica,  but  ammonia 
was  not  determined. 

These  results  are  so  irregular  that  definite  conclusions  can  hardly 
be  drawn  from  them.  A  and  B  agree  fairlj^  with  each  other,  and 
also  with  the  earlier  work  of  Schneider  and  Clarke.  C  contains  more 
ammonia,  but  differs  widely  from  B  as  to  the  amount  of  soluble  silica 
in  the  residue.  D,  which  represents  a  long  heating,  indicates  a  more 
complete  reaction  than  was  observed  in  either  of  the  other  cases. 

An  ammonium  compound,  however,  is  evidently  formed  during  the 
reaction,  although  its  precise  nature  can  not  be  determined  from  the 
evidence  now  in  hand.  Something  may  be  inferred  from  the  follow- 
ing figures,  which  are  to  be  summarized  thus:  First,  we  reproduce 
from  our  earlier  paper  the  analysis  of  the  pectolite  itself.  Secondly, 
we  give  the  analysis  of  the  insoluble  residue  obtained  in  experiment 
C.  The  third  column  of  figures  is  obtained  by  subtracting  from  the 
second  column  61.79  of  soluble  silica  and  1.18  of  hygroscopic  water, 
and  recalculating  the  remainder  to  100  per  cent.  The  fourth  column 
contains  the  molecular  ratios  calculated  from  the  third. 


Pectolite. 

Residue 
found. 

Residue 
reduced. 

Ratios. 

SiOa                                                     -    -        

53.34 
.33 

33.23 

.45 

9.11 

75.98 
.08 
9.56 
.24 
1.84 
2.23 
1.18 
9.47 

37.74 

.19 

25.43 

.63 

4.89 

5.93 

0.629 

A1,0,                          .    --          --        

.002 

CaO 

.454 

MnO     

.009 

Na^O 

NH3                      

.079 
.349 

H2O  at  100° 

.27 

2.70 

.67 

H^O  above  100° 

25.19 

1.399 

CO,                -  -   

100. 10 

100. 58 

100. 00 

CLARKE  AND 
STEIGER 


]  WOLLASTONITE    AND    APOPHYLLITE.  39 


These  ratios  roughly  suggest  the  formation  of  a  salt  approximating 
in  composition  to  the  formula  R'aCaaSisOa-GlIaO,  in  which  R'  is  about 
two-thirds  ammonium  and  one-third  sodium.  The  large  amount  of 
water  found  was  doubtless  absorbed  during  the  process  of  leaching. 
Pectolite  itself  has  the  formula  NaHCaaSigOg,  so  that  the  existence  of 
a  hydrous  ammonium  pectolite  is  indicated;  a  conclusion  which  is 
probable  but  not  proved.  The  reaction  between  pectolite  and  ammo- 
nium chloride  is  possiblj^  simple  at  first,  but  followed  by  or  entangled 
with  secondarj?-  changes  which  obscure  the  results.  The  experiments 
are  interesting,  however,  as  showing  how  widely  pectolite  differs  from 
the  other  minerals  which  we  have  studied,  as  regards  the  ammonium 
chloride  reaction. 

WOLLASTONITE. 

The  only  data  relative  to  the  action  of  ammonium  chloride  upon 
wollastonite  are  those  given  in  the  original  paper  by  Schneider  and 
Clarke,  but  on  account  of  the  close  relationship  between  this  species 
and  pectolite  it  seems  desirable  to  reproduce  the  record  here.  The 
mineral  studied  was  from  Diana.  N.  Y.,  and  it  had  the  subjoined 
composition : 

SiOa 50.05 

AlA^FeA 1.13 

CaO 47.10 

NagO .--- undet. 

MgO .09 

H^O --.         .45 

98. 82 

After  two  heatings  with  ammonium  cliloride  in  an  open  crucible, 
36.98  per  cent  of  lime  became  soluble  in  water.  In  other  words,  a 
very  notable  decomposition  had  occurred,  as  in  the  case  of  pectolite. 
Since  wollastonite  is  an  anhydrous  mineral,  this  result  shows  that 
the  reaction  does  not  depend  upon  the  presence  of  hydroxyl. 

APOPHYLLITE. 

Upon  this  species  only  one  rather  crude  experiment  was  made,  and 
that  with  material  of  unknown  locality.  Heated  with  ammonium 
chloride  in  a  sealed  tube,  it  gave  up,  on  leaching  with  water,  21.59 
per  cent  of  lime  and  5.18  of  potassa.  The  residue  contained  only 
0.79  per  cent  of  ammonia.  Evidently  the  mineral,  like  pectolite  and 
wollastonite,  is  largely  decomposed  by  the  reagent;  but  it  is  uncertain 
whether  any  regular  ammonium  compound  is  formed.  It  must  be 
remembered  that  apophyllite  sometimes  contains  small  quantities  of 
ammonia,  and  hence  it  seems  that  a  more  complete  investigation  of  it 
is  desirable.  -v 


40  ACTION    OF   AMMONIUM    CHLORIDE    ON    SILICATES.       [bull.  207. 


DATOLITE. 

The  compact,  porcelain-like  datolite  from  Lake  Superior.  This 
was  heated  in  a  sealed  tube  with  ammonium  chloride  in  the  usual 
way.  After  leaching  the  product  with  water,  the  washed  residue  con- 
tained 91.09  per  cent  of  silica  and  1.17  of  ammonia.  Evidently  the 
datolite  molecule  had  been  thoroughly  broken  down,  with  nearly 
complete  removal  of  the  bases  and  the  boric  acid.  The  significance 
of  the  retained  ammonia,  however,  is  not  clear. 

EL^OLITE. 

On  account  of  their  interest  as  rock-forming  minerals,  the  three 
species  nephelite  var.  elaeolite,  sodalite,  and  cancrinite  were  studied 
consecutively  and  with  some  reference  to  one  another.  The  elseolite 
was  the  characteristic  material  from  the  elseolite-syenite  of  Litchfield, 
Me.,  and  had  the  following  composition: 

SiOa 45.91 

AI2O3 31.14 

FeaOs .34 

FeO . .23 

CaO .33 

Na.fi 14.60 

K2O 5.60 

H^Oat  100° .47 

H2O  above  100° .93 

CO2 .40 

99. 95 

Five  grams  of  mineral  were  thoroughly  mixed  with  20  grams  of 
ammonium  chloride  by  long  grinding  in  an  agate  mortar,  and  then 
heated  for  six  hours  in  a  sealed  tube  to  350°.  Even  during  the  grind- 
ing a  strong  smell  of  ammonia  was  noticeable,  and  upon  opening  the 
sealed  tube  after  heating,  a  slight  pressure  of  ammonia  gas  was 
observed.  On  extraction  with  water  the  following  bases  passed  into 
solution : 

FeA-Al203 0.29 

CaO . .07 

Alkalies  (calculated  as  soda) 2. 10 

The  residue  from  the  leach  water  was  dried  at  50°,  and  then  found 
to  contain  0.92  per  cent  of  ammonia.  These  figures  confirm  those 
obtained  in  a  much  less  careful  preliminary  experiment,  and  show 
that  elaeolite  is  but  slightly  affected  by  the  reagent. 


CT.ATIKE  AND"! 
STEIGER.     J 


CANCRINITE. 


41 


CANCRINITE. 

The  material  studied  was  the  well-known  bright  yellow  cancrinite 
from  Litchfield,  Me.,  and  an  analysis  of  it  gave  the  following  results: 

SiO^ 36.19 

AI2O3 29.24 

Fe^fis trace 

CaO   4.72 

Na^O 19.20 

K2O .14 

H2O. 4.15 

CO2 - - 6.11 

99.75 

Upon  boiling  the  powdered  mineral  for  fifteen  minutes  with  the 
standard  solution  of  sodium  carbonate,  0.55  per  cent  of  silica  went 
into  solution.  After  ignition,  only  0.32  per  cent  was  soluble.  No 
silica,  therefore,  had  been  split  off  by  heating. 

With  ammonium  chloride  two  experiments  were  made.  In  each 
case  the  mineral  was  intimately  ground  with  four  times  its  weight  of 
the  chloride,  and  heated  to  350°  in  a  sealed  tube  for  four  hours. 
During  grinding  a  strong  smell  of  ammonia  was  noticed,  and  still 
more  was  given  off  when  the  tubes  were  opened.  The  products  were 
leached  with  water,  and  the  thoroughly  washed  residues  were  ana- 
lyzed, as  follows : 


SiO. 

AlA 

CaO 

Na,0(+K20) . 

NH3 

HjOatlOO"..- 
H2O  above  100 
CO. 


99.85 


B. 


37.48 

37.51 

31.23 

31.98 

5.10 

5.30 

7.78 

7. 53 

4.73 

3.77 

1.29 
12.24 

} 

14.48 

none 

none 

100. 57 


In  the  wash  water  from  product  B,  11.73  per  cent  of  the  original 
soda  was  found,  with  no  lime,  and  0.16  per  cent  of  silica  and  alumina. 
Somewhat  less  than  two-thirds  of  the  soda  had  been  taken  out.  The 
lime  seems  to  be  much  more  stably  combined,  and  water  was  taken 
up,  probably  in  the  process  of  leaching.  The  carbonic  acid  of  the 
cancrinite  had  been  completely  eliminated. 


42 


ACTION    OF    AMMONIUM    CHLOEIDE    ON"   SILICATES.       [bull.  207. 


Apparently,  if  the  product  of  tlie  reaction  is  a  definite  compound, 
the  effect  of  the  ammonium  chloride  has  been  to  transform  the  cancri- 
nite  into  a  zeolitic  body,  approximating  roughly  to  the  general  formula 


RiAlSiO^.  H2O, 

but  with  a  small  excess  of  the  univalent  bases.  Analysis  A, 
adjusted  by  rejecting  the  1.29  per  cent  of  hygroscopic  water,  and 
recalculation  of  the  remainder  to  100  per  cent,  assumes  the  following 
form  and  gives  the  appended  ratios: 


Analysis  re- 
duced. 

Ratios. 

SiOs                                                                           --  

38.03 

31.69 

5.17 

7.89 

4.80 

12.42 

0.634 

AI2O3 --- 

CaO                                                                        -  -     --- 

.311 
.093 

NaaO                   -                                          -            -          . 

.127 

NH3 : 

.282 

H2O  -     J 

.690 

100.00 

The  substance  is  evidently  not  absolutely  pure,  a  condition  which 
might  have  been  expected.  Any  closer  attempt  at  precise  formula- 
tion would  therefore  be  useless.  It  most  nearly  resembles,  among 
the  products  which  we  have  obtained,  the  ammonium  derivative  of 
thomsonite. 

SODALITE. 

Dark-blue  sodalite  from  Kicking  Horse  Pass,  British  Columbia. 
Analysis  as  follows: 

SiO^ 39.66 

AlA 30.09 

Fe^Og .31 

CaO -.. . .18 

Na^O 22.60 

K,0 1.14 

H^OatlOO" .17 

H,0  above  100" .79 

CI 6.12 

101.06 
LessO=Cl 1.39 

99.67 

With  ammonium  chloride  two  preparations  were  made,  both  by 

the  sealed-tube  method  at  350°.     In  A  the  heating  lasted  twenty-four 

hours;  and  in  B  six  hours.     From  residue  A,  by  leaching  with  water, 

2.96  per  cent  of  alkali,  reckoned  as  soda,  was  extracted;  and  from  B, 


CLARKE  AND 
STEIGER 


] 


SODALITE    AND    THE    FELDSPARS. 


43 


3.53  per  cent.     In  the  washed  residues  the  following  determinations 
were  made,  but  complete  analysis  seemed  to  be  unnecessary. 


A. 

B. 

SiO^ 

A1..0,(Fe,Oo) 

39.33 
31.40 

.20 
20.86 

.45 
5.92 

40.00 
32. 34 

CaO 

Na.,0(K20) ... 

NH3 _-     

.72 

CI         -                              -     -     _     -- 

Evidently  the  amount  of  change  was  slight,  and  no  definite  ammo- 
nium derivative  had  been  formed. 

In  one  way  these  results  shed  some  light  upon  the  constitution  of 
sodalite.  According  to  Lemberg  and  his  pupils  the  mineral  is  a  double 
salt,  a  molecular  compound  of  sodium  chloride  with  a  silicate  like 
nepheline.  If  this  view  were  correct  sodium  and  chlorine  should  be 
removed  together  by  the  action  of  a  decomposing  reagent.  We  find, 
however,  that  about  3  per  cent  of  soda  was  removed  from  sodalite  in 
forming  residue  A,  while  practically  all  of  the  chlorine  remains 
behind.  So  far,  then,  the  evidence  is  adverse  to  the  view  just  cited 
and  favorable  to  that  of  Brogger,  which  assigns  the  mineral,  as  an 
atomic  compound,  to  a  place  in  the  garnet  group. 

On  the  other  hand,  sodium  chloride  may  be  volatilized  from  sodalite 
by  prolonged  heating.  Two  portions  of  the  mineral  were  each  heated 
for  four  hours  over  a  blast-lamp  flame,  losing  10.80  and  10.72  per  cent, 
respectivelj^  The  chlorine  in  the  mineral,  6.12  per  cent,  corresponds 
to  10.08  per  cent  of  NaCl;  to  this  must  be  added  the  0.91  of  water 
found,  making  a  total  possible  loss  of  11.01  per  cent.  In  the  residue 
from  the  first  lot  ignited  0.20  of  chlorine  was  found,  so  that  the  vola- 
tilization of  sodium  chloride  had  been  almost  complete.  This  reac- 
tion, however,  taking  place  at  a  very  high  temperature,  may  be  only 
a  result  of  metathesis,  and  not  by  any  means  a  proof  that  sodium 
chloride,  as  such,  is  an  essential  constituent  of  sodalite.  The  evi- 
dence derived  from  the  ammonium  chloride  reaction  is  entitled  to  the 
greater  weight. 

THE   FELDSPARS. 

The  results  which  we  have  obtained  with  these  important  rock- 
forming  minerals  are  interesting  only  in  so  far  as  they  show  a  trifling 
sensitiveness  on  the  part  of  the  several  species  toward  dissociating 
ammonium  chloride.  The  action  upon  them  is  slight,  and  ammonium 
derivatives  do  not  seem  to  be  formed.  The  data  may  be  briefly  sum- 
marized as  follows : 

Ortlioclase. — From  southeastern  Pennsjdvania,  exact  locality 
unknown.     Quite  pure  cleavage  masses.     Heated  for  six  hours  with 


44  ACTION    OF    AMMONIUM    CHLORIDE    ON    SILICATES.       [bull.  207. 

ammonium  chloride  to  350°  in  a  sealed  tube,  and  leached  with  water, 
1.52  per  cent  of  KCl  went  into  solution.  The  residue,  dried  at  50°, 
contained  0.20  per  cent  of  ammonia. 

Oligoclase. — The  transparent  variety  from  Bakersville,  N.  C. 
Treated  like  the  orthoclase.  In  the  leach  water  0.96  per  cent  of  lime 
and  2.71  of  soda  were  found.  The  air-dried  residue  contained  1.47 
per  cent  of  ammonia.  It  is  barely  possible  that  in  this  case  an  ammo- 
nium derivative  may  have  been  produced,  but  the  data  are  not  posi- 
tive enough  to  warrant  any  definite  conclusion. 

Albite. — Well-crystallized  and  very  pure  material  from  Amelia 
Courthouse,  Ya.  Treated  like  the  two  preceding  feldspars.  Upon 
leaching,  0.12  percent  of  lime  and  0.84  of  soda  went  into  solution. 
In  the  residue,  dried  at  50°,  0.32  per  cent  of  ammonia  was  retained. 

OLIVINE. 

Green,  transparent  pebbles  from  near  Fort  Wingate,  N".  Mex. 
Examined  by  Schneider  and  Clarke,  who  employed  only  the  open 
crucible  method.  By  treatment  with  ammonium  chloride  only  0.44 
per  cent  of  magnesia  was  rendered  soluble  in  water — i.  e.,  converted 
into  magnesium  chloride.  In  view  of  the  ready  solubility  of  this 
mineral  in  even  weak  aqueous  acids,  this  lack  of  sensitiveness  to 
ammonium  chloride  is  somewhat  remarkable. 

ILVAITE. 

This  rare  mineral  was  found  by  Mr.  Waldemar  Lindgren  at  the 
Golconda  mine,  South  Mountain,  Owyhee  County,  Idaho.  It  occurs 
in  jet  black  masses  and  occasional  rough  crystals,  embedded  in  quartz 
or  calcite,  and  intimately  associated  with  two  other  minerals  which 
appear  to  be  garnet  and  tremolite.  Traces  of  pyrite  also  appear. 
The  specific  gravity  of  the  ilvaite,  as  determined  by  Dr.  Hillebrand, 
is  4.059  at  31°. 

Upon  grinding  the  powdered  mineral  with  ammonium  chloride  in 
an  agate  mortar,  a  distinct  smell  of  ammonia  was  noticeable.  Three 
tubes  of  the  mixture  were  heated  to  350°,  and  one  exploded  because 
of  the  liberation  of  gas  within.  Upon  opening  the  second  and  third 
tubes,  a  strong  outrush  of  ammonia  was  observed.  When  the  con- 
tents of  these  tubes  were  leached  with  water,  large  quantities  of 
ferrous  chloride  went  into  solution,  which,  rapidly  oxidizing,  formed 
a  deposit  of  brownish  hydroxide,  and  interfered  seriously  with  filtra- 
tion. The  greater  part  of  the  lime  in  the  ilvaite  was  dissolved  also. 
The  washed  residue,  containing  much  ferric  hydroxide,  was  partially 
analyzed,  and  enough'  data  were  obtained  to  show  that  a  general 
breaking  down  of  the  ilvaite  molecule  had  been  effected.  Apparently, 
also,  small  quantities  of  an  ammonium  derivative  had  been  formed; 


CLARKE  and! 
STEIGER.      J 


ILVAITE    AND    RIEBECKITE. 


45 


but  this  point  is  uncertain.  The  original  rainei-al  was  analyzed  by 
Dr.  W.  F.  Hillebrand,  and  his  analysis,  contrasted  with  that  of  the 
leached  residue,  is  here  given: 


Ilvaite  (Hille- 
brand). 

Residue 

(Steiger).     ■ 

SiO,...     - 

39.16 
.52 

30.40 

39.14 
5.15 

13.02 
.15 
.08 

43. 01 

Al^Os 

40. 08 

FeA 

FeO 

8.75 

MnO 

.85 

CaO 

2.25 

MgO 

undet. 

Na20 .--. 

Tindet. 

NH3 

.88 

H20at  105°--- .-'- 

.15 

2.64 

undet. 

H2O  above  105° 

undet. 

CI 

(a) 

100. 41 

95. 82 

a  Small  amount. 

In  the  leached  residue  from  the  third  tube  21.37  percent  of  soluble 
silica  was  found — silica  which  had  been  liberated  during  the  reaction 
between  the  ilvaite  and  the  ammonium  chloride.  In  short,  ilvaite 
behaves  toward  the  reagent  much  like  pectolite,  and  the  product  is  a 
mixture  of  uncertain  character.  The  evident  instability  of  the  ilvaite 
molecule  may  account  for  its  rarity  as  a  mineral  species.  Only 
exceptional  conditions  would  favor  its  formation. 


RIEBECKITE  (?). 

The  results  obtained  with  ilvaite  made  it  desirable  to  study,  for 
comparison,  some  other  silicates  of  iron.  Among  these  the  mineral 
from  St.  Peters  Dome,  near  Pikes  Peak,  Colorado,  originally  described 
by  Koenig  as  arfvedsonite,  but  identified  by  Lacroix  as  near  riebeck- 
ite,  happened  to  be  available.  It  was  treated  with  ammonium  chlo- 
ride in  the  usual  way  and  no  presence  of  liberated  gas  was  noticed 
when  the  tube  was  opened.  On  leaching  the  product  with  water,  fer- 
rous chloride  went  into  solution  and  ferric  hydroxide  with  some 
manganic  hydroxide  was  deposited.  In  the  leached  mass  6.90  per 
cent  of  soluble  silica  was  found,  and  in  the  wash  water  from  the 
leaching  there  was  6.76  per  cent  of  soda.  According  to  Koenig's 
analj'sis  the  mineral  contains  8.33  percent  of  soda,  so  that  a  large 
portion  of   the  total  amount  had  been  extracted.     There  was  also, 


46 


ACTION    OF    AMMONIUM    CHLOEIDE    ON    SILICi^TES.       [bull.  207. 


evidently,  a  considerable  breaking  down  of  the  molecule,  but  no 
definite  ammonium  derivative  had  been  formed.  This  is  shown  by 
the  following  analysis  of  the  leached  residue,  which  is  contrasted 
with  Koenig's  published  analysis'^  of  the  original  mineral  in  order  to 
indicate  the  amount  of  change.  In  the  third  column  of  figures  we 
give  the  amount  of  each  constituent  which  could  be  dissolved  out 
from  the  residue  by  treatment  with  hydrochloric  acid. 


Riebeckite 
(Koenig). 

Residue 

(Steiger). 

Soluble 
portion. 

SiOj-- 

49.83 

1.43 

.75 

14.87 

18.86 

1.75 

.41 

67. 54 

TiO, 

ZrOs 

FeoO, 

21.28 

4.94 

.64 

none 

trace 

I            1.04 

.53 

3.33 

trace 

15.74 

FeO 

4.94 

MnO : 

.64 

MgO -_     __. 

CaO 

NaaO  --. 

8.33 
1.44 

K2O 

NH3 _ 

.53 

H2O 

.20 

CI 

97.87 

99.30 

The  residue  is  evidently  a  mixture  of  free  silica  and  ferric  hydrate 
with  probably  at  least  two  silicates,  one  soluble,  the  other  insoluble 
in  hydrochloric  acid.  The  reaction  itself  is  noteworthy  because  of 
the  fact  that  the  original  mineral  is  but  slightly  attacked  when  boiled 
with  strong  hydrochloric  acid.  The  other  minerals  so  far  studied  by 
us  are  all  easily  decomposable  by  acids,  while  this  one  is  quite  refrac- 
tory. The  energetic  character  of  the  ammonium  chloride  reaction  is 
thus  strongly  emphasized. 

iEGIRITE. 

Material  from  the  well-known  locality  at  Magnet  Cove,  Arkansas. 
Not  absolutely  pure,  but  somewhat  contaminated  by  ferric  hydroxide. 
This  impurity  is  evident  in  a  discussion  of  the  ratios  furnished  by 
the  analysis,  but  is  not  serious.  It  does  not  affect  the  problems  under 
consideration.  By  heating  with  ammonium  chloride  the  mineral  was 
only  slightly  changed.     In  the  leach  water  from  the  product  there 


'Dana's  System  of  Mineralogy,  6tli  ed.,  p.  400. 


CLARKE  AND   1 
STEIGER.      J 


^GIRITE    AND    CALAMINE. 


47 


were  l.<3<i  per  cent  (AlFe)203,  0.51  CaO  and  1.18  Na^O.     Analyses  as 
follows:  A  of  the  segirite,  B  of  the  air-dried,  leached  residue. 


A. 

B. 

SiO^ 

AI2O3 . 

50. 45 

2.76 

23.42 

5.26 

.10 

1.48 

5.92 

9.84 

.24 

} 

} 
} 

51.83 

FeA 

FeO 

25.  24 
5. 69 

MnO . 

MgO 

CaO -     - 

1.58 
5.74 

Na^O ! 

K^O 

NH3 

9. 07 
.26 

H^OatlOO" 

.15 

.40 

H2O  above  100° - 

.90 

100. 02 

100.81 

Of  the  silica  in  the  residue  4.42  per  cent  was  soluble  in  sodium  car- 
bonate solution.     An  ammonium  derivative  was  not  formed. 

From  these  data  we  see  that  the  three  iron  silicates  are  verj^  differ- 
ently attacked  by  ammonium  chloride ;  ilvaite  very  strongly,  riebeck- 
ite  moderately,  and  segirite  but  feebly.  The  segirite  is  the  most 
stable  and  at  the  same  time  the  commonest  of  the  three.  A  com- 
parison of  the  segirite  analysis  with  that  made  by  J.  Lawrence  Smith 
of  material  from  the  same  region  shows  notable  differences.  The 
mineral  evidently  varies  in  composition,  the  variation  depending 
upon  the  relative  amounts  of  the  two  silicate  molecules  FeNaSigOg 
and  R"Si03.  Two  samples  taken  from  different  parts  of  the  same 
rock  area  are  not  necessarily  identical  in  composition. 


CALAMINE. 

The  simplest  constitutional  formula  for  calamine,  the  one  which  is 
generally  accepted,  represents  it  as  a  basic  metasilicate, 

Si03=(ZnOH)2.- 

In  this  the  hydrogen  is  all  combined  in  one  way,  and  so,  too,  is  the 
zinc.  In  all  other  possible  formulse,  simple  or  complex,  the  hydrogen 
as  well  as  the  zinc  must  be  represented  as  present  in  at  least  two 
modes  of  combination;  a  condition  of  which,  if  it  exists,  some  evidence 
should  be  attainable.  Our  experiments  upon  calamine  have  had  this 
point  in  view;  and  we  have  sought  to  ascertain  whether  water  or  zinc 
could  be  split  off  in  separately  recognizable  fractions.  Our  results, 
in  the  main,  have  been  negative,  and  tend  toward  the  support  of  the 


48  ACTION    OF    AMMONIUM    CHLORIDE    ON    SILICATES.       [bull.  207. 

usual  formula;  but  the  data  are  not  conclusive,  although  they  seem 
to  be  worthy  of  record. 

The  beautiful  white  calamine  from  Franklin,  N.  J.,  was  selected 
for  study,  and  gave  the  subjoined  composition: 

SiO^ 24.15 

AlA.  FeaOj --_: .19 

ZnO 67.55 

CaO .12 

H,0 ..   7.95 

99.96 
Fractional  ivater. 

At  100° 0.27 

At  180° .. .22 

At  250° . .75 

At  300° : .88 

Incipient  red  heat 4. 46 

Full  red  heat . 1.37 

7.95 
Here  no  clear  and  definite  fractionation  of  the  water  is  recognizable, 
at  least  of  such  a  character  as  to  suggest  any  other  than  the  ordinary 
formula  for  calamine. 

Upon  boiling  powdered  calamine  with  water,  practically  nothing 
went  into  solution,  but  by  boiling  with  the  solution  of  sodium  car- 
bonate 0.25  per  cent  of  silica  was  dissolved.  After  ignition  at  a  red 
heat,  only  0.14  per  cent  of  silica  became  soluble  in  sodium  carbonate; 
and  after  blasting,  only  0.24.  In  these  experiments  a  very  little  zinc 
was  dissolved  also ;  but  there  was  no  evidence  that  any  breaking  up 
of  the  mineral  into  distinguishable  fractions  had  occurred.  In  a  hot 
10  per  cent  solution  of  caustic  soda  both  the  fresh  and  the  ignited 
calamine  dissolve  almost  comjpletely;  but  boiling  with  aqueous  am- 
monia seems  to  leave  the  mineral  practically  unattacked.  All  exper- 
iments aiming  to  extract  a  definite  fraction  of  zinc  while  leaving  a 
similar  fraction  behind  resulted  negatively. 

By  heating  with  dry  ammonium  chloride  in  an  open  crucible,  cala- 
mine is  vigorously  attacked  and  gains  in  weight  by  absorption  of 
chlorine.  In  two  experiments  the  mineral  was  intimately  mixed  with 
three  times  its  weight  of  powdered  sal  ammoniac  and  heated  in  an  air 
bath  for  several  hours  to  a  temperature  somewhat  over  400°.  A  large 
part  of  the  residue  was  soluble  in  water,  and  the  percentage  of  this 
portion,  together  with  the  percentage  increase  in  weight,  is  given 
below : 


Grain  in  weight  _ . 
Soluble  in  water. 


27.60 
53.23 


25.78 
67.13 


^'^s^iGEt''"]  CALAMINE    AND    PYROPHYLLITE.  49 

A  conversion  of  calamine  into  the  clilorhydriji  Si().,(ZnCU).j  would 
involve  a  gain  in  weight  of  15.34  per  cent.  Complete  c(m  version  into 
2ZnCl2+Si02  implies  an  increase  of  38.14  per  cent.  The  figures  given 
lie  between  these  two,  and  are  indefinite  also  for  the  reason  that  there 
was  volatilization  of  zinc  chloride. 

In  two  more  experiments  the  calamine,  mingled  with  three  times 
and  four  times  its  weight  of  ammonium  chloride,  respectively,  was 
heated  for  an  hour  and  a  half  to  bright  redness  in  a  combustion  tube. 
The  zinc  chloride  which  was  formed  volatilized  and  was  collected  by 
suitable  means  for  determination.  It  corresponded  to  59. 0  and  59.0 per 
cent  of  tbe  original  mineral,  calculated  as  zinc  oxide,  which  indicates 
a  nearly  complete  decomposition  of  the  calamine  into  2ZnCl2+Si02. 
The  residue  was  mainlj^  silica,  with  a  small  part  of  the  zinc,  about 
half  of  the  silica  being  soluble  in  sodium  carbonate  solution.  Here 
again  no  definite  fractionation  of  the  mineral  could  be  observed. 

Finally  the  action  of  dry  hydrogen  sulphide  upon  calamine  was 
investigated.  The  mineral  was  heated  to  redness  in  a  current  of  the 
gas  and  gained  perceptiblj^  in  weight.  The  percentage  data,  reckoned 
on  the  original  calamine,  were  as  follows,  in  two  experiments : 

II. 

Gaininweight 6.00  6.43 

SiOa  soluble  in  NaaCOg. . , 16. 45  30. 95 

Sulphur  in  residue 24. 12 

Complete  conversion  of  calamine  into  2ZnS  +  Si02  implies  a  gain  in 
weight  of  5.80  per  cent,  and  it  is  therefore  evident  from  the  figures  of 
the  second  experiment  that  the  limit  of  change  was  approached  very 
nearly.  The  24.12  of  sulphur  taken  up  is  quite  close  to  the  26.53  per 
cent  which  is  required  by  theory.  About  eight-ninths  of  the  calamine 
had  undergone  transformation.  Again  no  definite  fractionation  was 
detected. 

The  hydrogen  sulphide  reaction  was  examined  still  further  with 
reference  to  the  temperature  at  which  it  becomes  effective.  Even  in 
the  cold  calamine  is  slightly  attacked  by  the  gas,  but  its  action  is 
unimportant  until  the  temperature  of  400°  is  approximated.  Then  it 
becomes  vigorous  and  the  reaction  goes  on  rapidly.  A  few  experi- 
ments with  willemite  showed  that  it  also  was  attacked  by  hydrogen 
sulphide,  but  less  vigorously  than  calamine. 

PYEOPHYLLITE. 

The  empirical  formula  for  pyrophyllite,  AlHSiaOg,  is  apparently 
that  of  an  acid  metasilicate,  and  the  mineral  is  therefore  peculiarly 
available  for  fractional  analysis.     The  compact   variety  from  Deep 

9506— No.  207—02 4 


50  ACTION    OF    AMMONIUM    CHLOEIDE    ON    SILICATES.       [bull.  207. 

River,  N.  C,  was  taken  for  examination,  and  a  uniform  sample  was 
prepared.     Analysis  gave  the  following  results: 

SiO^ 64.73 

Ti02 .73 

AI2O3 29.16 

Fe^Oj .49 

MgO trace 

Ignition 5. 35 

100. 46 

If,  now,  pyrophyllite  is  an  acid  metasilicate  it  should  break  up  on 
ignition  in  accordance  with  the  equation 

2AlHSi206=MSi309+Si02+H20. 

That  is,  one-fourth  of  the  silica,  or  16.18  per  cent,  should  be  liber- 
ated. The  mineral  itself  is  very  slightly  attacked  by  boiling  with  the 
sodium  carbonate  solution,  and  in  an  experiment  of  this  kind  only 
0.72  per  cent  of  silica  was  dissolved.  Upon  ignition  under  varying 
circumstances  the  following  data  M^ere  obtained : 

Ignited  ten  minutes  over  a  Bunsen  burner,  and  then  extracted  with 
sodium  carbonate  solution,  1.51  per  cent  of  SiOo  dissolved. 

Ignited  fifteen  minutes  over  a  Bunsen  burner,  1.89  per  cent  became 
soluble. 

Ignited  ten  minutes  over  a  Bunsen  burner  and  then  fifteen  minutes 
over  the  blast,  2.84  per  cent  of  silica  was  liberated. 

These  results  are  of  a  different  order  from  those  given  by  pectolite 
and  talc,  and  raise  the  question  whether  pyrophyllite,  despite  its 
ratios,  is  a  metasilicate  at  all.  So  far  as  the  evidence  goes,  it  may 
with  propriety  be  regarded  as  a  basic  salt  of  the  acid  HaSioOg,  and  its 
formula  then  becomes 

SioOg^Al-OlI. 

This  formula  is  at  least  as  probable  as  the  metasilicate  ex]3ression, 
which  latter  rests  upon  assumption  alone.  Still  other  formulae,  but 
of  greater  coniplexit}^  are  possible;  but  until  we  know  more  of  the 
genesis  and  chemical  relationships  of  pyrophyllite,  speculation  con- 
cerning them  would  be  unprofitable. 

By  heating  with  ammonium  chloride  in  an  open  crucible  pyrophyl- 
lite is  very  slightly  attacked.  In  two  experiments  it  lost  in  weight 
6.17  and  6.30  per  cent,  respectively.  The  excess  of  loss  over  water  is 
due,  as  we  have  proved,  to  the  volatilization  of  a  little  ferric  and 
aluminic  chloride.  The  residue  of  the  mineral  after  this  treatment 
contained  no  chlorine,  so  that  no  chlorhydrin-like  body  had  been 
formed.  The  formation  of  such  a  compound,  the  replacement  of 
hydroxyl  by  chlorine,  would,  if  it  could  be  effected,  be  a  valuable 
datum  toward  determining  the  actual  constitution  of  the  species. 
The  sealed  tube  experiments  were  not  attempted. 


CliAIlKE  and! 
BTElGEil.      J 


SEEPENTINE    AND   PHLOOOPITE. 


51 


SERPENTINE. 

In  1891  Clarke  and  Schneider  published  an  investigation  "  relative 
to  the  action  of  gaseous  hydrochloric  acid  upon  various  minerals. 
Among  these  were  the  three  species,  serpentine,  leuchtenbergite,  and 
phlogopite,  and  the  remainders  of  the  original  samples  were  fortu- 
nately at  our  disposal.  The  analyses  made  by  Schneider  are  there- 
fore directly  comparable  with  the  new  data  secured  by  us. 

The  serpentine,  from  Newburyport,  Mass.,  was  but  moderately 
attacked  upon  heating  with  ammonium  chloride.  Upon  leaching  the 
contents  of  the  sealed  tube  with  water,  0.18  per  cent  of  silica  and  5.23 
of  magnesia  went  into  solution.  The  washed  residue  and  the  serpen- 
tine had  the  following  composition : 


Serpentine 
(Schneider). 

Residue 

(Steiger) . 

SiOa  -._.. .        . 

41.47 

1.73 

41.70 

.09 

45.43 

Fe,0.,  ALO.. 

88 

MgO --                          ... 

39  54 

FeO . 

NH, . 

09 

H,0                 --       

15.06 

14  01 

100.05 

99.94 

The  leached  residue  contained  1.06  per  cent  of  soluble  silica.  The 
amount  of  change  effected  in  the  mineral  was  evidently  small,  and  no 
ammonium  compound  was  produced. 

In  Schneider  and  Clarke's^  paper  upon  the  ammonium  chloride 
reaction  a  serpentine  from  the  river  Poldnewaja,  district  of  Syssert, 
in  the  Urals,  was  studied.  By  a  single  treatment  in  an  open  crucible 
4.93  per  cent  of  magnesia  became  soluble  in  water  as  chloride.  In  a 
second  experiment  the  mineral,  after  heating  with  10  grams  of  ammo- 
nium chloride  until  volatilization  ceased,  was  reheated  with  10  grams 
more.  Upon  leaching,  14.30  per  cent  of  magnesia  went  into  solution. 
In  a  third  trial  the  serpentine  was  thrice  treated  and  only  10.63  per 
cent  of  magnesia  was  converted  into  chloride.  In  the  last  case  the 
residue  was  boiled  with  sodium  carbonate  solution,  which  extracted 
3.82  per  cent  of  silica.  The  same  serpentine  was  completely  decom- 
posable by  aqueous  hydrochloric  acid,  but  only  moderately  attacked 
by  the  dry  gas.  The  evident  irregularity  of  these  results  is  yet  unex- 
plained. 

PHLOGOPITE. 

From  Burgess,  Canada.  The  contents  of  the  sealed  tube,  after 
heating,  showed  little  appearance  of  change.  The  leach  water  con- 
tained magnesia.     Analyses  as  follows: 

aBuU.  U.  S.  Geol.  Survey  No.  78,  p.  11, 1891.       &Bull.  U.  S.  Geol.  Survey  No.  113,  p.  34, 1893. 


52 


ACTION    OF    AMMONIUM    CHLORIDE    ON    SILICATES.       Lbull.  ii07. 


Phlogopite 
(Schneider). 

Residue 

(Steiger). 

SiOa      -      -                             --               

39.66 
.56 

17.00 
.27 
.20 
.62 

26.49 

.60 

9.97 

45. 03 

TiO, 

AI2O3                                                 -       --- 

15.07 

Fe,Oo              ^                                                _-_ 

FeO                                                                        - 

BaO  .  -  -         

MgO                -          

24.94 

Na^O                              --    - 

.94 

K2O                                        ---   - - 

8.69 

NH3 

.21 

H,0              --     

2.99 

2.24 

5.01 

F                           

Less  0     . --     - .-.- 

100.60 
.94 

99.89 

99.66 

The  residue,  on  boiling  with  sodium  carbonate,  gave  0.40  per  cent 
of  soluble  silica.  From  these  data  it  appears  that  phlogopite  is  some- 
what attacked  by  ammonium  chloride,  but  not  strongly.  No  definite 
ammonium  derivative  is  formed. 

LEUCHTENBERGITE. 

From  the  standard  locality  near  Slatoust,  in  the  Urals.  When  the 
contents  of  the  sealed  tube  were  leached  with  water,  there  passed  into 
solution  0.19  per  cent  of  alumina,  plus  iron,  2.10  of  magnesia,  and 
2.03  of  lime.  The  residue  was  not  completely  analyzed,  but  the  few 
determinations  made  contrast  with  Schneider's  results  as  follows : 


Leuchtenberg- 
ite. 

Residue 
(Steiger). 

SiO^     -- 

32.27 
16.05 

4.26 

.28 

29.75 

6.21 

32.82 

ALO,-     - 

Fe-fis            -     --   -     - 

FeO                      --   

MgO                       - 

CaO                            __    .  . 

4.67 

NHo                          .--   ,.     .-.   - 

.25 

H2O --- 

11.47 

12.11 

100. 29 

^^s'^xSni''"]       LEUCHTENBERGITE    AND    XANTH6PHYLLITE.  58 

No  definite  ammonium  compound  was  formed,  and  ilie  amount  of 
decomposition  was  small.  As  the  lime  shown  by  the  analysis  is  at 
least  partly  due  to  the  presence  of  garnet  as  an  impurity  in  the  min- 
eral, it  will  be  interesting  to  determine  the  effect  producible  by 
ammonium  chloride  upon  that  species. 

In  Schneider  and  Clarke's  investigation,  conducted  in  open  cruci- 
bles, this  same  leuchtenbergite,  after  three  heatings  with  ammonium 
chloride,  gave  up  3.08  jier  cent  of  magnesia  upon  leaching  with  Avater. 
The  residue  contained  a  little  magnesium  oxychloride.  With  clino- 
chlore  from  Slatoust  similar  results  were  obtained.  A  double  heating 
with  ammonium  chloride  extracted  2.12  per  cent  of  magnesia,  and  a 
triple  heating  took  out  3.80  per  cent. 

XANTHOPHYLLITE. 

Varietj^  waluewite,  from  the  Nikolai-Maximilian  mine,  district  of 
Slatoust,  Urals.  Examined  by  Schneider  and  Clarke,  who  found  the 
mineral  to  be  practically  unattacked  bj'  gaseous  hydrochloric  acid, 
but  completely  decomposable  by  the  aqueous  acid.  A  triple  treating 
with  ammonium  chloride  in  an  open  crucible  took  out  0.48  per  cent  of 
lime  and  0.61  of  magnesia.  This  amount  of  decomposition  is  insig- 
nificant. 

THE   ACTION   OF   AMMONIUM   CHLORIDE   ON   ROCKS. 

From  the  evidence  so  far  presented  it  is  clear  that  the  ammonium- 
chloride  reaction  has  much  theoretical  interest  and  that  it  adds  a 
good  deal  to  our  knowledge  of  chemical  constitution.  But  does  it  go 
any  further  than  this  and  render  au}^  assistance  in  the  elucidation  of 
other  problems?  Consider,  for  instance,  the  rational  analj^sis  of 
silicate  rocks — that  is,  the  quantitative  determination  of  certain  min- 
eral constituents  as  distinguished  from  the  ordinary  estimation  of  the 
oxides — is  the  reaction  of  any  service  here?  We  have  found  that 
among  the  rock-forming  minerals  analeite  and  leucite  are  completely 
transformable  into  ammonium  salts,  while  elseolite  and  the  feldsjiars 
are  but  little  affected;  olivine  and  the  ferro-magnesian  silicates  also 
react  but  slightly.  It  would  seem,  therefore,  as  if  analeite  and  leucite 
might  be  approximately  determined  by  means  of  the  reaction,  the 
amount  of  change  produced  in  a  rock  mixture  being  some  measure  of 
their  quantity.  To  test  this  supposition,  we  have  made  a  number  of 
experiments,  using  for  the  purpose  well-known  rocks  which  had  been 
studied  both  mineralogicallj^  and  chemically. 

Our  method  of  procedure  has  been  extremely  simple,  and  no  refine- 
ments of  process  have  as  yet  been  attempted.  Each  rock,  in  fine 
powder,  was  mixed  with  four  times  its  weight  of  ammonium  chloride 
and  heated  for  several  hours  in  a  sealed  tube  to  350°.  After  cooling, 
the  mixture  was  leached  with  water,  and  the  amount  of  alkali  pass- 
ing into  solution  was  estimated.  From  this  soluble  alkali  the  amount 
of  analeite  or  leucite  in  the  rock  may  be  be  roughly  inferred,  but  of 


54 


ACTIOTSr    OF    AMMONIUM    CHLORIDE    ON"    SILICATES.       [bull.  207. 


course  not  with  any  great  degree  of  accuracy.  Still  an  approximate 
estimation  is  better  than  no  measurement  at  all  and  is  of  service  to 
the  petrographer.  Fortunately  the  errors  of  the  process  are  to  some 
extent  compensatory;  a  little  analcite  or  leucite  will  always  escape 
transformation,  while  on  the  other  hand  a  little  alkali  will  always  be 
yielded  bj^  other  species.  One  error  renders  the  estimation  of  the 
alkali  too  low,  the  other  makes  it  high,  but  the  two  tend  to  balance 
each  other.  In  the  ordinary  process  for  separating  soluble  from 
insoluble  silicates  by  means  of  aqueous  hydrochloric  or  very  dilute 
nitric  acid  the  same  errors  occur,  but  with  additional  complications 
due  to  the  solution  of  magnesian  minerals  like  olivine.  Furthermore, 
aqueous  acids  will  not  discriminate  between  analcite  and  nepheline, 
two  species  which  behave  very  differently  toward  dissociating  ammo- 
nium chloride.  So  much  premised,  we  may  pass  on  to  the  description 
of  our  experiments. 

First,  we  examined  three  rocks  from  the  Leucite  Hills,  Wyoming, 
which  were  analyzed  by  Hillebrand  and  described  by  Cross."  Their 
mineralogical  composition  is  as  follows : 

A.  Orendite.  Contains  predominating  leucite  and  sanidine,  with  plilogopite,  a 
little  biotite,  diopside,  and  amphibole,  and  accessory  apatite  and  rutile. 

B.  Wyomingite.  Contains  plilogopite,  leucite,  diopside,  and  apatite. 

C.  Madnpite.  Contains  predominating  diopside  and  phlogopite,  with  perofskite 
and  magnetite,  in  a  glassy  base,  which  has  approximately  the  composition  of 
lexicite. 

On  A  and  B  duplicate  determinations  were  made,  but  onl}^  one  in 
the  case  of  C.  The  substances  extracted  by  leaching,  after  treatment 
with  ammonium  chloride,  are  given  below : 


Al. 

A  2. 

Bl. 

B2. 

0.64 
1.70 
9.38 
1.35 

C. 

AI2O,,  FejO, 

0.26 

1.28 

4.68 

.25 

0.21 

1.48 

4.53 

.43 

0.64 
1.67 
9.  50 
1.33 

0.21 

CaO                 -  -     

5.06 

K2O                            -         -     - 

6.81 

NaaO - - 

1.08 

The  duplicates  are  fairty  concordant.     If  now  we  regard  the  KgO 
thus  extracted  as  a  measure  of  the  leucite  in  each  rock,  giving  the 
mineral  its  normal  composition  KAlSigOg,  we  have  the  following  per- 
centages of  the  latter : 
In  orendite: 

1 - 21.81 

3 __.  21.11 

In  wyomingite: 

1 ..44.47 

2 43.71 

In  madnpite 31 .  73 

« Am.  Jour.  Sei.,  4th  series,  Vol.  IV,  p.  115.    See  also  Bull.  U.  S.  Geol.  Survey  No.  168,  pp.  8.5  and 
86,  1900,  for  analyses. 


CLARKE  AND 
STEIGEB 


]        AOTION    OF    AMMONIUM    CHLORlDE    ON    ROCKS. 


55 


Two  other  leucite  rocks  were  also  studied  hy  us,  us  follows,  both 
being  given  in  dujjlicate: 

D.  MissoiTi-ite.  Highwood  Monntains.  Montana.  Described  by  Weed  and  Pirs- 
son."  Analyzed  by  E.  B.  Hnrlbnt.  Contains  angite  and  leucite,  with  apatite, 
iron  oxides,  olivine,  and  biotite.     Some  zeolites  and  analcite  are  also  present. 

E.  LeiTcitite.  Bearpaw  Monntains,  Montana.  Described  by  Weed  and  Pirsson. '' 
Analyzed  by  H.  N.  Stokes.  An  olivine-free  leucite  basalt.  Contains  leucite, 
augite,  iron  oxides,  rarely  biotite.  and  a  very  small  amount  of  glassy  base. 

The  following  substances  were  taken  out  bj^  the  ammonium  chlo- 
ride reaction : 


Dl. 

D2. 

El. 

E3. 

CaO 

K.0 .     

Na.,0 .    _    .. 

1.73 

4.09 

.59 

1.70 

3.74 

.64 

0.89 
6.19 
1.44 

1.29 
6.16 

1  47 

Hence  we  have  for  leucite — 


In  missourite  _ . 19. 06  and  17. 43 

In  leucitite 28. 84  and  28.  70 

It  will  be  observed  that  the  extracted  soda  is  neglected  in  the  com- 
putation. In  missourite  it  may  rej)resent  analcite;  in  the  other 
rocks  it  perhaps  belongs  to  a  sodium  equivalent  of  leucite,  or  it  may 
come  from  some  still  different  source.  At  all  events,  it  serves  to  indi- 
cate some  of  the  uncertainties  attending  the  application  of  the 
method. 

Among  the  rocks  containing  analcite  as  an  essential  constituent, 
only  two  were  available  for  our  purposes.     They  are: 

F.  Analcite-basalt,  from  Basin,  Colorado.  Described  by  Cross.  <"  Analyzed  by 
Hillebrand.  Contains  phenocrysts  of  augite,  olivine,  and  analcite;  also  mag- 
netite, and  minor  amounts  of  alkali  feldspars,  biotite,  and  apatite. 

Gr.  Heronite,  from  Heron  Bay.  Lake  Superior.  Described  by  Coleman.'^  Con- 
tains analcite,  orthoclase,  labradorite,  aegirite,  limonite,  and  calcite. 

By  treatment  with  ammonium  chloride  the  following  bases  were 
extracted  from  these  rocks,  determinations  being  made  in  duplicate: 


PI. 

F2. 

Gl. 

G2. 

CaO 

1.74 

.46 

8.42 

2.28 

.49 

3.29 

1.64 

.21 

6.04 

1.62 

K2O.  -           

.18 

NaP---             

6.37 

"Am.  Jom-.  Sci.,  4tli  series.  Vol.  II,  p.  815;  Bull.  U.  S.  Geol.  Survey  No.  168,  p.  133. 
&  Am.  Jour.  Sci.,  4th  series,  Vol.  II,  p.  143;  Biill.  U.  S.  Geol.  Survey  No.  168,  p.  136. 
cSee  BuU.  U.  S.  Geol.  Survey  No.  168,  p.  146. 
d  Jour.  Geology,  Vol.  VH,  p.  431. 


56 


ACTION    OF    AMMONIUM    CHLOEIDE    ON    SILICATES.       [bull.  207. 


Hence,  reckoning  the  soda  as  equivalent  to  normal  analcite, 
NaAlSiaOg-HgO,  we  have  as  percentages  of  the  latter: 

In  analcite-basalt 26. 33  and  25, 33 

Inheronite _. 46.51  and  49.05 

According  to  Coleman's  computations,  heronite  contains  47  per  cent 
of  analcite.  This  figure  agrees  quite  perfectly  with  our  experimental 
determination. 

In  order  to  gain  some  notion  of  the  extent  to  which  other  rocks, 
containing  neither  analcite  nor  leucite,  might  be  affected  bj'  the 
reaction  with  ammonium  chloride,  four  examples  were  chosen  from 
among  the  many  which  have  been  studied  in  this  laboratory.^'  They 
were : 

H.  Phonolite,  Uvalde  County.  Tex.  Contains  sanidine,  nepheline,  and  segirite, 
with  very  little  brown  hornblende,  augite,  and  magnetite. 

I.  Soda-granite-porphyry,  Merced  River,  Mariposa  County,  Cal.  Contains  feld- 
spar, largely  albite,  hornblende,  miTscovite,  epidote,  apatite,  and  iron  ore. 

J.  Granitite,  Placerville  Canal,  Eldorado  County.  Cal.  Conta.-'ns  biotite,  ortho- 
clase,  plagioclase,  and  qtiartz. 

K.  Augite-latite,  Table  Moimtain,  Tnolnmne  County,  Cal.  Contains  labra- 
dorite,  olivine^  atigite,  and  magnetite. 

The  bases  extracted  from  these  four  rocks  were  as  follows,  in 
percentages : 


H. 

I. 

J. 

K. 

AI2O3,  FejOs 

CaO                                     -         -       --  - 

0.33 
.22 
.41 

4.38 

0.19 
.29 
.20 
.33 

0.58 

none 

.20 

.23 

0.66 

K2O  .       

1.21 

Na^O .--- 

.66 

Among  these  rocks  only  the  first  one,  the  phonolite,  was  seriously 
affected;  and  it  is  diiiicult  to  account  for  the  large  amount  of  soda 
extracted.  Neither  nepheline  nor  segirite  taken  alone  gives  up  nearly 
so  much  soda  as  was  liberated  in  this  case,  and  no  other  sodium  min- 
eral has  been  reported  present  in  the  rock.  In  the  other  cases  the 
amount  of  extraction  is  small  and  amounts  to  no  more  than  the  plus 
error,  which  was  pointed  out  at  the  beginning  of  this  discussion. 

Taking  all  things  into  account,  it  seems  probable  that  the  analytical 
method  proposed,  although  far  from  exact,  is  capable  of  some  devel- 
opment, and  is  likely  to  yield  results  of  some  value.  Perhaps  it  might 
be  improved  by  taking  into  account  the  quantities  of  ammonia  retained 
by  the  washed  residues.  From  that  source  one  estimate  could  be 
derived,  and  from  the  alkali  in  solution  another;  the  two  should  give 
better  information  than  either  determination  alone.  But  the  jpreci- 
sion  of  ordinary  analytical  processes  is  not  to  be  expected  here,  and 
only  useful  approximations  can  be  anticipated. 


oFor  aflditionul  data  and  the  analyses,  see  Bull.  U.  S.  Geol.  Survey  No.  168,  pp.  62, 199,  20.5,  31)7. 


^"^s^S/h^'^J  summary.  57 

SUMMARY. 

lu  the  foregoing  X)ag6s  we  have  considered  the  action  of  ammonium 
chloride,  at  its  temperature  of  dissociation,  upon  31  mineral  species. 
We  have  shown  that  its  influence  upon  various  silicates  differs  very 
widely,  but  that  in  general  it  is  a  much  more  powerful  reagent  than  has 
been  generally  supposed.     The  results,  in  brief,  are  as  follows: 

First.  Analcite,  leucite,  natrolite,  and  scolecite,  lieated  with  dry 
ammonium  chloride  to  350°  in  a  sealed  tube,  yield  alkaline  chlorides 
and  an  ammonium  aluminum  silicate,  which  is  stable  at  300°.  The 
reaction  is  simply  one  of  double  decomposition,  the  sodium  or  potas- 
sium of  the  original  silicate  being  completely  replaced  by  ammonium. 
Analcite  and  leucite  give  the  same  product,  NH4AlSi20y.  Natrolite 
and  scolecite  yield  the  salt  (NH4)2Al2Si30io.  The  latter  coxnpound  is 
a  derivative  of  orthotrisilicic  acid,  IlgSi^Ojij;  and  in  a  separate  sec- 
tion of  the  memoir  its  constitution  and  its  relations  to  other  trisilicic 
acids  are  considered. 

Second.  A  similar  reaction,  a  double  decomposition,  takes  j)lace 
incompletel}^  with  stilbite,  heulandite,  chabazite,  thomsonite,  laumont- 
ite,  and  pollucite.  Part  of  the  monoxide  base  is  removed  and  replaced 
by  ammonium,  without  change  of  atomic  ratios.  Cancrinite  is  also 
vigorously  attacked,  and  partially  transformed  into  a  zeolitic  body. 

Third.  Pectolite,  woUastonite,  apophj^llite,  datolite,  ilvaite,  and 
calamine  are  violently  acted  upon  by  ammonium  chloride,  and  their 
molecules  seem  to  be  almost  completely  broken  down.  The  products 
of  the  reactions  are  mixtures,  and  no  ammonium  silicates  are  formed. 

Fourth.  Elfeolite,  sodalite,  riebeckite,  olivine,  serpentine,  phlogo- 
pite,  prehnite,  orthoclase,  albite,  oligoclase,  segirite,  pyrophyllite, 
leuchtenbergite,  and  xanthophyllite  are  but  slightly  attacked  by  dis- 
sociating ammonium  chloride. 

In  the  closing  section  of  the  work  we  have  shown  that  the  ammonium 
chloride  reaction  may  be  applied  to  an  approximate  quantitative 
determination  of  analcite  and  leucite  in  rocks,  thereby  aiding  some- 
what in  the  estimation  of  their  mineralogical  composition. 

O 


PUBLICATIONS  OF  UNITED  STATES  GEOLOGICAL  SURVEY. 

[BnlU'tiii  No.  207.] 

The  serial  publications  of  the  United  States  Geological  Survey  consist  of  (1)  Annual 
Reports,  (2)  Monographs,  (3)  Professional  Papers,  (4)  Bulletins,  (5)  Mineral  Resources, 
(())  Water-Supply  and  Irrigation  Papers,  (7)  Topographic  Atlas  of  United  States — 
folios  and  separate  sheets  thereof,  (8)  Geologic  Atlas  of  United  States? — folios  tiiereof. 
The  classes  numbered  2,  7,  and  8  are  sold  at  cost  of  publication;  the  others  are  dis- 
tributed free.     A  circular  giving  complete  lists  may  be  had  on  application. 

The  Bulletins,  Professional  Pajjers,  and  Water-Supply  Papers  treat  of  a  variety  of 
sul)jects,  and  the  total  number  issued  is  large.  They  have  therefore  been  classified 
into  the  following  series:  A,  Economic  geology;  B,  Descriptive  geology;  C,  Systematic 
geology  and  paleontology;  D,  Petrography  and  mineralogy;  E,  Chemistry  and 
physics;  F,  Geography;  G,  Miscellaneous;  H,  Forestry;  I,  Irrigation;,  J,  Water 
storage;  K,  Pumping  water;  L,  Quality  of  water;  M,  Methods  of  hydrographic  investi- 
gation; N,  Water  power;  O,  Underground  waters;  P,  Hydrographic  progress  rejiorts. 
This  bulletin  is  the  thirty-sixth  in  Series  E,  the  complete  list  of  whi(th  follows  (all 
are  liuUetins  thus  far) : 

SERIES  E,  CHEMISTRY  AND  PHYSICS. 

9.  Report  of  work  done  in  the  Washington  In.boratory  during  tlie  fiscal  year  1883-8-1,  bj'  F.  W. 
Clarke  and  T.  M.  Chatard.    1884.    40  pp. 
14.  Electrical  and  magnetic  properties  of  the  iron  carburets,  by  Carl  Barus  and  Vincent  Stronhal. 

1885.  238  pp. 

27.  Report  of  work  done  in  the  Division  of  Chemistry  and  Physics,  mainly  during  the  year  1884-85. 

1886.  80  pp. 

32.  Lists  and  analyses  of  the  mineral  springs  of  the  United  States  (a  preliminary  study),  by  Albert 
C.  Peale'.    1886.    235  pp. 

35.  Physical  properties  of  the  iron  carburets,  by  Carl  Barus  and  Vincent  Strouhal.    1886.    62  pp. 

36.  Subsidence  of  fine  solid  particles  in  liquids,  by  Carl  Barus.    1886.    58  pp. 

42.  Report  of  work  done  in  the  Division  of  Chemistrj"^  and  Physics,  mainly  during  the  fiscal  year 
1885-86,  by  F.  VV.  Clarke.    1887.    152  pp.,  1  pi. 

47.  Analyses  of  waters  of  the  Yellowstone  National  Park,  with  an  account  of  the  methods  of 
analyses  employed,  by  Frank  Austin  Gooch  and  James  Edward  Whitfield.    1888.    84  pp. 

52.  Subaerial  decay  of  rocks  and  origin  of  the  red  color  of  certain  formations,  by  Israel  Cook 
Russell.    1889.  65  pp.,  5  pis. 

54.  On  the  thermoelectric  measurement  of  high  temperatures,  by  Carl  Barus.    1889.    313  pp.,  11  pis. 

.55.  Report  of  work  done  in  the  Division  of  Chemistry  and  Physics,  mainly  during  the  fiscal  year 
1886-87,  by  Frank  Wigglesworth  Clarke.    1889.    96  pp. 

60.  Report  of  work  done  in  the  Division  of  Chemistry  and  Physics,  mainly  during  the  fiscal  year 
1887-88.     1890.     174  pp. 

64.  Report  of  work  done  in  the  Division  of  Chemistry  and  Physics,  mainly  during  the  fiscal  year 
1888-89,  by  F.  W.  Clarke.    1890.    60  pp. 

68.  Earthquakes  in  California  in  1889,  by  James  Edward  Keeler.    1890.    25  pp. 

73.  The  viscosity  of  solids,  by  Carl  Barus.    1891.    xii,  139  pp.,  6  pis. 

78.  Report  of  work  done  in  the  Division  of  Chemistry  and  Physics,  mainly  during  the  fiscal  year 
1889-90,  by  F.  W.  Clarke.    1891.    131  pp. 

90.  Report  of  work  done  in  the  Division  of  Chemistry  and  Physics,  mainly  during  the  fi.scal  year 
1890-91,  by  F.  W.  Clarke.    1892.    77  pp. 

92.  The  compressibility  of  liquids,  by  Carl  Barus.    1892.    96  pp.,  29  pis. 

94.  The  mechanism  of  solid  viscosity,  by  Carl  Barus.    1892.    138  pp. 

95.  Earthquakes  in  California  in  1890  and  1891,  by  Edward  Singleton  Holden.    1892.    31  pp. 

96.  The  volume  thermodynamics  of  liqnid.s,  by  Carl  Barus.    1892.    100  pp. 

I 


II         PUBLIC A.TIONS    OF    UNITED    STATES    GEOLOGICAL    SURVEY. 

103.  High  temperature  work  in  igneous  fusion  and  ebullition,  chiefly  in  relation  to  pressure,  by 
Carl  Barus.    1893.    57  pp.,  9  pis. 

112.  Earthquakes  in  California  in  1892,  by  Charles  D.  Perrine.    1893.    57  pp. 

113.  Report  of  work  done  in  the  Division  of  Chemistry  and  Physics  during  the  fiscal  years  1891-92 
and  1892-93,  by  F.  W.  Clarke.    1893.    115  pp. 

114.  Earthquakes  in  California  in  1893,  by  Charles  D.  Perrine.    1894.    23  pp. 

125.  The  constitution  of  the  silicates,  by  Frank  Wigglesworth  Clarke.    1895.    100  pp. 
129.  Earthquakes  in  California  in  1894,  by  Charles  D.  Perrine.    1895.    25  pp. 

147.  Earthquakes  in  California  in  1895,  by  Charles  D.  Perrine.    1896.    23  pp. 

148.  Analyses  of  rocks,  with  a  chapter  on  analytical  methods,  laboratory  of  the  ITnitod  States 
Geological  Survey,  1880  to  1896,  by  F.  W.  Clarke  and  W.  F.  Hillebrand.    1897.    306  pp. 

155.  Earthquakes  in  California  in  1896  and  1897,  by  Charles  D.  Perrine.    1898.    47  pp. 
161.  Earthquakes  in  California  in  1898,  by  Charles  D.  Perrine.    1899.    31  pp.,  1  pi. 

167.  Contributions  to  chemistry  and  mineralogy  from  the  laboratory  of  the  United  States  Geological 
Survey;  Frank  W.  Clarke,  Chief  Chemist.    1900.    166  pp. 

168.  Analyses  of  rocks,  laboratory  of  the  United  States  Geological  Survey,  1880  to  1899,  tabulated 
by  F.  W.  Clarke.    1900.    308  pp. 

176.  Some  principles  and  methods  of  rock  analysis,  by  W.  F.  Hillebrand.    1900.    114  pp. 
186.  On  pyrite  and  marcasite,  by  H.  N.  Stokes.    1900.    50  pp. 

207.  The  action  of  ammonium  chloride  upon  silicates,  by  F.  W.  Clarke  and  George  Steiger.    1902. 
57  pp. 

Correspondence  should  be  addressed  to — 

The  DiRECTOE, 

United  States  Geological  Survey, 

Washington,  D.  C. 
November,  1902. 


LIBRAEY  CATALOGUE  SLIPS. 


[Take  this  leaf  out  and  paste  the  separated  titles  upon  three  of  your  catalogue 
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United  States.     Department  of  the  interior.     (  U.  S.  Geological  survey. ) 
Bulletin  No.  207     Series  E,  Chemistry  and  physics,  36  |  Depart- 
ment of  the  interior  |  United  States  geological  survey  |  Charles  D. 
Walcott,  director  |  —  |  The  |  action  of  ammonium  chloride  j  upon 
silicates  |  by  |  Frank  Wiggles  worth  Clarke  |  and  |  George  Steiger  | 
[Vignette]  | 
Washington  |  government  printing  office  |  1902 
8°.    57  pp. 


Clarke  (Frank  Wigglesworth)  and  Steiger  (George). 

Bulletin  No.  207    Series  E,  Chemistry  and  physics,  36  |  Depart- 
ment of  the  interior  |  United  States  geological  survey  |  Charles  D. 
Walcott,  director  |  —  |  The  |  action  of  ammonium  chloride  |  uj^on 
silicates  |  by  |  FrankWigglesworth  Clarke  |  and  |  George  Steiger  | 
[Vignette]  | 

Washington  |  government  printing  office  |  1902 

8°.    67  pp. 


Bulletin  No.  207     Series  E,  Chemistry  and  physics,  36  |  Depart- 
ment of  the  interior  |  United  States  geological  survey  |  Charles  D. 
Walcott,  director  |  —  |  The  |  action  of  ammonium  chloride  |  upon 
silicates  |  by  |  FrankWigglesworth  Clarke  |  and  |  GeorgeSteiger  | 
[Vignette]  1 

Washington  |  government  printing  office  |  1902 

8°.    57  pp. 


BOSTON  COLLEGE 


3  9031    026  22807  2 


